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Background and Purpose: The prognosis of acute basilar artery occlusion (BAO) is poor if early recanalization is not achieved. Recanalization strategies include intravenous thrombolysis (IVT) and intra-arterial thrombolysis, as well as endovascular mechanical thrombectomy (EMT). The combination of IVT with consecutive on-demand EMT may allow for early treatment initiation with high recanalization rates but has never been systematically tested in patients with BAO., Methods: Starting in January 2006, we treated all eligible patients with acute BAO admitted to our academic stroke center or one of our cooperating community hospitals after a standardized protocol combining IVT with consecutive on-demand EMT. Inclusion criteria were: (1) presence of predefined symptoms clearly suggestive of BAO; (2) exclusion of intracerebral hemorrhage on CT scan; (3) evidence of BAO on CT angiography; (4) start of therapy within 6 hours after symptom onset; and (5) no contraindications for IVT. If CT angiography showed persistent BAO after IVT, EMT was performed., Results: Since January 2006, 16 patients have been treated. All patients received IVT; in 7 of them, EMT became necessary because of persistent BAO. Final recanalization was achieved in 15 patients. Three months after therapy, 12 of 16 patients were still alive; 7 of them had a good outcome (modified Rankin score

Sargahydroquinoic acid (2), a major active constituent of Sargassum micracanthum collected from the coast of the East Sea in Korea, showed a selective vasodilatation effect on the basilar arteries of rabbits. Therefore, treatment with sargahydroquinoic acid may selectively accelerate cerebral blood flow through dilatation of the basilar artery without lowering systemic blood pressure.

Diabetes increases the risk of stroke and contributes to poor clinical outcomes in this patient population. Myogenic tone of the cerebral vasculature, including basilar arteries, plays a key role in controlling cerebral blood flow. Increased myogenic tone is ameliorated with ET receptor antagonism in Type 1 diabetes. However, the role of endothelin-1 (ET-1) and its receptors in cerebrovascular dysfunction in Type 2 diabetes, a common comorbidity in stroke patients, remains poorly elucidated. Therefore, we hypothesized that 1) cerebrovascular dysfunction occurs in the Goto-Kakizaki (GK) model of Type 2 diabetes, and 2) pharmacological antagonism of ETA receptors ameliorates, while ETB receptor blockade augments vascular dysfunction. GK or control rats were treated with antagonists to either ETA (atrasentan, 5 mg.kg(-1).day(-1)) or ETB (A-192621, 15 or 30 mg.kg(-1).day(-1)) receptors for 4 wk and vascular function of basilar arteries was assessed using a wire myograph. GK rats exhibited increased sensitivity to ET-1. ET(A) receptor antagonism caused a rightward shift, indicating decreased sensitivity in diabetes, while it increased sensitivity to ET-1 in control rats. Endothelium-dependent relaxation was impaired in diabetes. ETA receptor blockade restored relaxation to control values in the GK animals with no significant effect in Wistar rats and ETB blockade with 30 mg.kg(-1).day(-1) A-192621 caused paradoxical constriction in diabetes. These studies demonstrate that cerebrovascular dysfunction occurs and may contribute to altered regulation of myogenic tone and cerebral blood flow in diabetes. While ETA receptors mediate vascular dysfunction, ETB receptors display differential effects. These results underscore the importance of ETA/ETB receptor balance and interactions in cerebrovascular dysfunction in diabetes.

We investigated the histamine responsiveness of basilar arterial rings isolated from chicken. We also examined whether endothelial cells were involved in the histamine responsiveness and in resting vascular tone. Histamine induced concentration-dependent relaxations under condition of precontraction by 5-hydroxytryptamine. The concentration-response curve for histamine was shifted to the right by diphenhydramine (a H(1) receptor antagonist), cimetidine (a H(2) receptor antagonist) and Nomega-nitro-L-arginine (L-NNA, a nitric oxide synthase inhibitor); however, indomethacin (a cyclooxygenase inhibitor) had no significant effect on it. Treatment with L-NNA shifted the concentration-response curve of histamine to the right in the presence of cimetidine, but not in the presence of diphenhydramine. Treatment with cimetidine shifted the concentration-response curve of histamine to the right in the presence of diphenhydramine. L-NNA induced a contraction but indomethacin had no effect on the resting vascular tone. These results suggest that histamine-induced relaxation is mediated via activation of H(1) receptors located on endothelial cells and H(2) receptors located on smooth muscle cells. The main relaxing factor released from endothelial cells is probably nitric oxide. The resting vascular tone was modulated by spontaneously released nitric oxide, but not by prostaglandins or thromboxane A(2).

Transcranial Doppler (TCD) is a non-invasive method for measuring blood flow velocity (BFV), and a marker of vessel diameter. In this study, intracranial BFV was investigated, by means of TCD, in patients suffering from probable medication-overuse headache (PMOH). Twenty-three female patients with probable ergotamine- overuse headache (PEOH), 23 female patients with probable analgesic-overuse headache (PAOH), and 15 healthy female controls participated in the study. The mean BFVs of the bilateral middle and anterior cerebral arteries (MCA and ACA) and basilar artery (BA) were measured by TCD. The mean BFVs of the BA and MCA were found to be significantly increased in the PEOH group when compared with those of the PAOH and control groups (p<0.05). No significant differences in BFV of the ACA were observed between any groups (p>0.05). The mean BFV of all the vessels in the PAOH group was found to be lower than that of the control group but no statistical significance was found (p>0.05). Our results show that ergotamine increases BFV via vasoconstriction, especially of the BA and MCA. We also suggest that 5HT1B/1D receptors are mainly localized in the BA and MCA, and that analgesic overuse results in a functional disorder of neuronal receptor and neurovascular reflexes and may cause a reduction of intracerebral vessel tone, leading to vasodilatation.

Angiotensin II type 1 receptor (AT1R) blocker (ARB) has been reported to modify hypertensive cerebrovascular changes; however, it is not clear whether its protective effects are independent of blood pressure. The aim of this study was to clarify the role of AT1R-mediated signals in cerebral circulation by the chronic treatment with telmisartan, an ARB, at a dose that did not lower the blood pressure. Male spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY) were treated for 4 weeks from 16 weeks of ages with telmisartan (SHR-L: 0.3 mg/kg/day, SHR-H: 3 mg/kg/day, WKY-H: 3 mg/kg/day) or vehicle (SHR-V, WKY-V). Superoxide measured by a chemiluminescent assay or dihydroethidium fluorescence and vascular morphology were examined for the thoracic aorta (Ao), common carotid (CCA), middle cerebral (MCA) and basilar arteries (BA). After 4 weeks of treatment, the blood pressure significantly declined in SHR-H but not in SHR-L in comparison to SHR-V. The lower limit of cerebral blood flow (CBF) autoregulation, evaluated by hemorrhagic hypotension, was significantly lower in SHR-L and SHR-H than SHR-V. In both SHR and WKY, the superoxide levels in the arteries were significantly attenuated by both doses of ARB. ARB also reversed vascular hypertrophy in Ao, CCA and BA and the inward remodeling in MCA. These results suggest that chronic treatment with telmisartan may therefore improve CBF autoregulation with a restoration of the vascular structure and an attenuation of superoxide generation, even at a dose that does not lower the blood pressure.

Inflammatory processes may play a pivotal role in the pathogenesis of cerebrovascular injury in salt-loaded stroke-prone spontaneously hypertensive rats (SHRSP). Recent reports revealed that acetylsalicylic acid (aspirin) has anti-oxidative properties and elicits nitric oxide release by a direct activation of the endothelial NO synthase. The present study was designed to determine whether low-dose aspirin might prevent cerebrovascular injury in salt-loaded SHRSP by protecting oxidative damage. Nine-week-old SHRSP were fed a 0.4% NaCl or a 4% NaCl diet with or without treatment by naproxen (20 mg/kg/day), salicylic acid (5 mg/kg/day), or aspirin (5 mg/kg/day) for 5 weeks. Blood pressure, blood brain barrier impairment, mortality, and the parameters of cerebrovascular inflammation and damage were compared among them. High salt intake in SHRSP significantly increased blood brain barrier impairment and early mortality, which were suppressed by treatment with aspirin independent of changes in blood pressure. Salt loading significantly increased superoxide production in basilar arteries of SHRSP, which were significantly suppressed by treatment with aspirin. Salt loading also significantly decreased NOS activity in the basilar arteries of SHRSP, which were significantly improved by treatment with aspirin. At 5 weeks after salt loading, macrophage accumulation and matrix metalloproteinase-9 activity at the stroke-negative area in cerebral cortex of SHRSP were significantly reduced by treatment with aspirin. These results suggest that low-dose aspirin may exert protective effects against cerebrovascular inflammation and damage by salt loading through down-regulation of superoxide production and induction of nitric oxide synthesis.

Object: The gap junction is important in the propagation of dilation/constriction signals along vessels for coordinated behavior in control of vascular tone. The authors hypothesized that gap junctions might play a role in cerebral vasospasm following subarachnoid hemorrhage (SAH). The aims of the present study were to investigate the role of gap junctions and to observe the potential therapeutic efficacy of gap junction blockers in cerebral vasospasm in vitro and in vivo., Methods: For the in vitro investigation, the effect of heptanol on the oxyhemoglobin (HbO(2))-induced contraction of isolated rabbit basilar arteries (BAs) was observed by using an isometric tension-recording method. For the in vivo experiments, the potential therapeutic efficacy of heptanol and carbenoxolone was surveyed after it was given intravenously in the rabbit double-hemorrhage model. Light microscopy was performed to assess the morphological changes in the arteries examined., Results: For the in vitro method, heptanol significantly inhibited the sustained contraction induced both by HbO(2) and K(+) in the BA rings. The magnitude of the heptanol-induced relaxation was dose dependent. The inhibitory effect of heptanol on the K(+)-induced vasoconstriction was weaker than that on the HbO(2)-induced constriction. After arterial rings were pretreated for 10 minutes, heptanol significantly decreased their responses to the HbO(2)-induced contraction. For the in vivo method, heptanol and carbenoxolone significantly decreased the narrowing of BAs when given intravenously in the rabbit double-hemorrhage model. In both treated groups, the diameters of the arteries had not changed significantly on Day 7 compared with those of the arteries in the SAH + vehicle and the SAH-only group., Conclusions: Heptanol and carbenoxolone significantly inhibited the experimental cerebral vasospasm both in vitro and in vivo. Blockage of gap junctions is a probable candidate for a new approach in the treatment of cerebral vasospasm. Gap junctions may play a pathophysiological role in cerebral vasospasm.

The aim of this study was to assess the role of K(+) and Ca(2+) fluxes in the cerebroarterial vasoactive effects of the phosphodiesterase-5 inhibitor sildenafil. We used isolated rabbit basilar arteries to assess the effects of extracellular K(+) raising on sildenafil-induced vasodilatation, and studied the pharmacological interaction of sildenafil with selective modulators of membrane K(+) and Ca(2+) channels. Expression of Kv1 subunits of K(+) channels was assessed at messenger and protein levels. Parallel experiments were carried out with zaprinast for comparison. Sildenafil (10 nM-0.1 mM) induced concentration-dependent relaxation of endothelin-1 (10 nM)-precontracted arteries, which was partially inhibited by depolarization with KCl (50 mM), 3 mM tetraethylammonium (non-selective K(+) channel blocker) or 1 mM aminopyridine (inhibitor of K(v) channels), but not by 1 microM glibenclamide (inhibitor of K(ATP) channels) or 50 nM iberiotoxin (inhibitor of K(Ca) channels). Arterial smooth muscle expressed messengers for Kv1.2, Kv1.3, Kv1.4, Kv1.5 and Kv1.6, and proteins of Kv1.1, Kv1.2 and Kv1.4. CaCl(2) (10 microM- 10 mM) induced concentration-dependent contraction in Ca(2+)-free, depolarizing (50 mM KCl) medium. Sildenafil (0.1-100 microM) produced reversible concentration-dependent inhibition of the response to CaCl(2), which was completely abolished by the highest sildenafil concentration. By contrast, only 100 microM zaprinast inhibited the response to CaCl(2). The L-type Ca(2+) channel activator Bay K 8644 (0.1 nM-1 microM) induced concentration-dependent potentiation of the response to CaCl(2) inhibited by 100 microM sildenafil. Moreover, Bay K 8644 (0.1 nM-1 microM) induced concentration-dependent contraction in slightly depolarizing (15 mM) medium, which was inhibited to the same extent and in a concentration-dependent way by sildenafil (0.1-100 microM) and zaprinast (1 or 100 microM). These results show that sildenafil relaxes the rabbit basilar artery by increasing K(+) efflux through K(v) channels, which in turn may affect Ca(2+) signalling. Expression of Kv1 subunits involved in this pharmacological effect occurs at the messenger and, in some cases, at the protein level. In addition to this phosphodiesterase-5-related effect, sildenafil and zaprinast inhibit cerebroarterial vasoconstriction at least in part by directly blocking L-type Ca(2+) channels, although a decrease in the sensitivity of the contractile apparatus to Ca(2+) can not be discarded.

Addition of N-acetylcysteine induced relaxation of the coronary and basilar arteries thus indicating some basilar NO-stores in these vessels. The maximum capacity of the NO-stores was similar in the coronary and the basilar arteries. Following adaptation to hypoxia, however, the depot was much greater in the coronary artery wall. This seems to be connected with different degree of participation of the NO-dependent vasodiatation in implementation of the adaptive response to hypoxia in coronary and cerebral vascular systems.

The endovascular perforation rodent model for experimental subarachnoid hemorrhage (SAH) studies is criticized for lack of control over bleeding. Presently, there is no practical grading system to categorize the severity of SAH depending on the amount of blood. We outline a simple and objective novel SAH grading system by examining the subarachnoid blood clots in the basal cisterns, and evaluate for correlation with neurological status and cerebral vasospasm. Effects of simvastatin, known to reduce vasospasm, were examined using this grading system. Seventy-seven adult male Sprague-Dawley rats were divided randomly into three groups: sham-operated (n=24), SAH (n=32), and SAH+simvastatin (n=25). High-resolution brain pictures were used to grade the severity of SAH and categorize animals into mild, moderate and severe groups. The SAH grades were compared with neurological scores and internal carotid artery parameters such as diameter, perimeter and wall thickness at 24h. Two investigators verified the grading system independently. The SAH grade showed linear correlation functionally with neurological status (r=0.42, p<0.01) and morphometrically with the degree of vasospasm (|r|>0.7, p<0.01), and also between two independent investigators (r=0.937, p<0.001). Simvastatin improved neurological score in moderate and severe (p<0.05) but not mild SAH groups (p=0.28). This grading system has the potential to be adopted for SAH experimental rodent models.

Background: Recent studies have demonstrated that apoptosis in cerebral arteries could play an essential role in cerebral vasospasm after subarachnoid hemorrhage (SAH) and that SP600125, an inhibitor of c-Jun N-terminal kinase (JNK) could suppress apoptosis. The present study examined whether SP600125 could reduce cerebral vasospasm through the suppression of apoptosis., Method: Fifteen dogs were assigned to 3 groups: control, SAH, and SAH + SP600125 (30 micromol/l). SAH was induced by the injection of autologous blood into the cisterna magna on day 0 and day 2. Angiograms were evaluated on day 0 and day 7. The activation of the JNK pathway and caspase-3 were also evaluated using Western blot. To determine the distribution, TUNEL staining and immunohistochemistry for phosphorylated c-jun and cleaved caspase-3 were performed., Findings: Severe vasospasm was observed in the basilar artery of the SAH dogs. SP600125 reduced angiographic and morphological vasospasm and reduced the expression of cleaved caspase-3, thereby suppressing apoptosis., Conclusions: These results demonstrate that SP600125 attenuates cerebral vasospasm through the suppression of apoptosis, which may provide a novel therapeutic target for cerebral vasospasm.

Background and Purpose: Rho-kinase (ROK)-mediated Ca2+ sensitization of vascular smooth muscle (VSM) contraction plays a pivotal role in cerebral vasospasm (CV). We previously demonstrated that sphingosylphosphorylcholine (SPC) induces Ca2+ sensitization through sequential activation of the Src family protein tyrosine kinases (Src-PTKs) and ROK in vitro, and that Ca2+ sensitization is inhibited by eicosapentaenoic acid (EPA) through the selective inactivation of Src-PTK. In this study, we examined whether SPC induced CV in vivo, and, if it did, whether EPA would inhibit CV, as induced by SPC or in an in vivo model of subarachnoid hemorrhage (SAH)., Methods: Changes in the diameter of the canine basilar artery were investigated by angiography after administering SPC into the cisterna magna. Then, Y27632, a specific Rho-kinase inhibitor, or EPA was injected intracisternally and the effects of both agents were investigated. In another experiment using a single-hemorrhage model, Y27632 or EPA was injected on day 7 after SAH and the changes in the diameter of the canine basilar artery were investigated., Results: At cerebrospinal fluid concentrations of 100 and 300 micromol/l, SPC induced severe vasoconstriction (maximum vasoconstriction by SPC (100 micromol/l): 61.8 +/- 8.2%), which was markedly reversed by Y27632 (96.3 +/- 4.4%) or EPA (92.6 +/- 12.8%). SAH caused severe vasospasm on day 7 (67.6 +/- 7.8%), which was significantly blocked by Y27632 (95.5 +/- 10.6%) or EPA (90.0 +/- 4.4%)., Conclusions: SPC is a novel mediator of ROK-induced CV in vivo. The inhibition of CV induced by SPC or after SAH by EPA suggests beneficial roles of EPA in the treatment of CV. Our findings are compatible with the notion that the SPC-ROK pathway may be involved in CV., ((c) 2008 S. Karger AG, Basel)

Background: Delayed cerebral ischemia due to cerebral vasospasm remains a major cause of morbidity and mortality following subarachnoid hemorrhage. Oxyhemoglobin (OxyHb) and vasoconstrictor prostanoids have been suggested as putative spasmogens. We have previously reported a synergistic vasoconstrictive action between thromboxane A(2) (TXA(2)) and OxyHb. In the present study we examine the effect of neomycin, a phospholipase C inhibitor, on the cerebral vasoconstriction induced by TXA(2) and OxyHb., Methods: Using an in vitro tissue bath method, we assess the effect of neomycin in a concentration-dependent manner, on isolated porcine basilar arteries constricted by U-46619 (TXA(2) analogue) and OxyHb., Results: The functional synergism between TXA(2) and OxyHb, leading to significant cerebral vasoconstriction, is attenuated in a dose-dependent manner by neomycin., Conclusion: Blockade of phospholipase C may provide an alternative strategy in the treatment of subarachnoid-hemorrhage-induced cerebral vasospasm., ((c) 2008 S. Karger AG, Basel.)

The aim of this study was to investigate whether total stenosis of the common carotid artery (ipsilateral) would affect the vascular responsiveness of the contralateral carotid as well as the basilar artery from guinea pigs. With this purpose, the carotid artery was occluded with a silk thread at a position close to its origin. Vascular reactivity experiments using standard muscle bath were performed 7, 15, 30, and 90 days after carotid occlusion. Stenosis induced a progressive reduction in the contraction induced by endothelin-1, phenylephrine and KCl in the ipsilateral carotid, when compared to their respective age-matched SHAM groups. Endothelial removal or incubation of endothelium-intact ipsilateral carotids with L-NAME, a nitric oxide synthase inhibitor, did not alter the response to endothelin-1 or phenylephrine, when compared to the endothelium-intact ipsilateral carotid in the absence of the inhibitor. Interestingly, an increased contractile response to endothelin-1, phenylephrine and KCl was observed in the contralateral carotid. Indomethacin, a non-selective cyclooxygenase inhibitor, prevented the increased contraction to endothelin-1 in the contralateral carotid. Stenosis also induced an increase in the contractile response to endothelin-1 in the basilar artery while the contractile response to phenylephrine and KCl were reduced. Indomethacin, but not L-NAME, prevented the increased contraction to endothelin-1 in the basilar artery. Morphometric analysis showed no differences in the medial area (wall thickness) of carotid or basilar arteries from the stenosis group when compared to their respective age-matched SHAM groups. The present study confirms the importance of adaptation to stenosis on the vascular reactivity of the stenosed artery to different vasoconstrictor agents. Moreover, our results show that stenosis induces alterations of the vascular reactivity on arteries distant from the site of injury. The increased response to endothelin-1 in the contralateral carotid artery and basilar artery seems to involve the release of vasoconstrictor prostanoids from endothelial origin.

The pharmacological nature of nicotine-induced contraction in the rat basilar artery is poorly understood. The purpose of this study was to investigate the endothelium dependency and involvement of arachidonic acid metabolites in nicotine-induced contraction in the rat basilar artery. The rat basilar artery was removed from the brain and cut into a spiral preparation. Nicotine (3x10(-5) to 10(-2) M) induced the concentration-dependent contraction in the rat basilar artery, and the maximal contraction was obtained at 3x10(-3) M. The contraction induced by nicotine (3x10(-3) M) was significantly attenuated by the presence of saponin (0.05 mg/ml, 15 min). Phospholipase C (PLC) inhibitors (NCDC and U-73122), calcium-independent phospholipase A(2) (iPLA(2)) inhibitor (BEL), cyclooxygenase-2 (COX-2) inhibitors (nimesulide, L-745,337 and celecoxib), and a 5-lipoxygenase (5-LOX) inhibitor (ZM-230487) concentration-dependently attenuated the nicotine-induced contraction. A cytosolic phospholipase A(2) (cPLA(2)) inhibitor (AACOCF3), secretory phospholipase A(2) (sPLA(2)) inhibitor (indoxam), and cyclooxygenase-1 (COX-1) inhibitors (flurbiprofen and ketoprofen) did not affect the nicotine-induced contraction. From these results, it was suggested that nicotine-induced contraction in the rat basilar artery is endothelium-dependent and is due to arachidonic acid metabolites.

Background and Purpose: The mechanism for the development of post-haemorrhagic cerebral vasospasm after subarachnoid haemorrhage (SAH) still remains unknown., Experimental Approach: We investigated the role of thrombin and its receptor PAR1 in the development of hyper-contractility of the basilar artery in a rabbit double haemorrhage model, which received two injections of autologous blood into the cisterna magna., Key Results: In the basilar artery isolated from the control rabbits, thrombin, only at 10 units ml(-1), induced a transient endothelium-dependent relaxation and a slight smooth muscle contraction. In SAH, the contractile response to thrombin was markedly enhanced, while the endothelium-dependent relaxant effect of thrombin remained unchanged. The enhancement of the contractile responses was also observed in the absence of endothelium and thrombin induced an enhanced contraction at concentrations higher than 0.3 units ml(-1). The contractile response to PAR1-activating peptide was also enhanced after SAH. However, the contractile responses to high K+ and endothelin-1, and the myofilament Ca2+-sensitivity remained unchanged after SAH. An immunoblot analysis suggested the up-regulation of PAR1 in the smooth muscle of the basilar artery. The heparinization of blood before injection prevented the enhancement of the contractile responses to thrombin and PAR1-activating peptide., Conclusions and Implications: The present study demonstrated, for the first time, that the contractile response of the basilar artery to thrombin was markedly enhanced after SAH. Mechanistically, our findings suggested that the activation of thrombin following hemorrhage up-regulated the expression of PAR1, thereby inducing the hyper-responsiveness to thrombin.

Background and Purpose: Information about early recanalization of basilar artery occlusion after systemic tissue plasminogen activator remains unknown. We aimed to determine the timing of recanalization in basilar artery occlusion treated with systemic thrombolysis, microbubbles, and continuous transcranial Doppler monitoring., Methods: We studied 20 patients with <12 hours basilar artery occlusion treated with intravenous tissue plasminogen activator, 2 hours continuous ultrasound, and 3 boluses of microbubbles. Transcranial Doppler assessed recanalization at different time points. Outcome was assessed using the National Institutes of Health Stroke Scale and modified Rankin scale. Patients were considered to be independent if modified Rankin scale score was <3 at 90 days., Results: Median admission National Institutes of Health Stroke Scale was 18.5 (interquartile range 16 to 26.5) and median time to treatment was 180 minutes (range, 80 to 720 minutes). Rate of complete recanalization raised progressively: at 1 hour 10%, at 2 hours 20%, at 6 hours 35%, and at 24 hours 50%. In 10 patients (50%), no recanalization was observed at 24 hours. Median discharge National Institutes of Health Stroke Scale was 14 (interquartile range 1 to 30). Degree of National Institutes of Health Stroke Scale improvement was related to time of recanalization: median discharge National Institutes of Health Stroke Scale--1 for recanalization between 0 and 6 hours, 11 for recanalization between 6 and 24 hours, and 30 if no recanalization occurred (P=0.002). At 3 months, mortality was 35%. Only one patient (10%) who recanalized within 24 hours died as compared with 60% of nonrecanalizers (P=0.029). Rate of independent patients progressively decreased as time to recanalization increased (P=0.006)., Conclusions: In acute basilar artery occlusion, endovenous tissue plasminogen activator, microbubbles, and continuous ultrasound leads to early recanalization in a significant number of patients and this is associated with favorable outcome. Immediate intravenous tissue plasminogen activator treatment should be the first therapeutic option in these patients.

We investigated the responsiveness of basilar arterial rings isolated from snakes to noradrenaline (NA), acetylcholine (ACh), histamine (His), 5-hydroxytryptamine (5-HT), mammalian bradykinin (BK) and rattlesnake BK. We also examined whether endothelial cells were involved in the responsiveness to ACh, BK, rattlesnake BK and in their resting vascular tone. NA and 5-HT induced concentration-dependent contractions. The cumulative concentration response curves of NA and 5-HT were shifted to the right in parallel by phentolamine (an alpha antagonist) and methiothepin (a 5-HT(1) and 5-HT(2) antagonist), respectively. However, ketanserin (a 5-HT(2) antagonist) had no effect on the cumulative concentration response curve of 5-HT. His, ACh, BK and rattlesnake BK had no effect on resting vascular tone; however, rattlesnake BK and sodium nitroprusside relaxed arteries precontracted by 5-HT. The rattlesnake BK-induced relaxations were almost abolished by L-nitro arginine (L-NA, a nitric oxide synthase inhibitor). L-NA and indomethacin (a cyclooxygenase inhibitor) had no effect on resting vascular tone or on precontracted arteries. These results suggest that alpha and 5-HT(1) receptor subtypes might be important in arterial contraction. Endothelial cells might play an important role in the responsiveness of snake basilar arteries to rattlesnake BK, but they might not be involved in the responsiveness to ACh, BK and in resting vascular tone.

Background: Though cerebral vasospasm is one of the most serious complications of subarachnoid haemorrhage (SAH), its complex pathogenesis is poorly understood and available clinical treatment options are unsatisfactory. This study was designed to examine the efficacy of leflunomide, an immunomodulatory agent with inhibitory properties, on vascular smooth muscle cell proliferation and inflammation in a rabbit cerebral vasospasm model., Methods: Twenty-two adult New-Zealand rabbits were assigned to 4 groups: control, SAH, SAH plus vehicle, SAH plus leflunomide. Subarachnoid haemorrhage was induced by administration of 1 ml of fresh unheparinised autologous arterial blood into the cisterna magna. Oral leflunomide (2 mg/kg) or vehicle treatment was started 12 h after the induction of subarachnoid haemorrhage and administered once a day. Three days later, the animals were sacrificed and the basilar artery was examined histologically for the lumen area and the thickness of the vessel wall. Inflammatory reaction was also examined by counting white blood cells within the vessel wall by means of light microscopic examination using haematoxylin and eosin staining., Findings: Severe and moderate vasospasms were detected in the basilar artery of the SAH and SAH plus vehicle treated groups, respectively. Leflunomide effectively reduced the vasospasm of the basilar artery. Compared to the vehicle treated group, leflunomide significantly reduced the lumen area (p < 0.01) and hyperplasia of the vessel wall (p < 0.01). Although inflammatory response within the vessel wall was reduced in the leflunomide treated group, no statistical significance was found between groups (p = 0.07)., Conclusion: This study demonstrates for the first time that leflunomide treatment attenuates cerebral vasospasm in a rabbit SAH model while inflammatory reaction in the vessel wall is not affected. Although further studies are needed to reveal its molecular mechanisms in relieving vasospasm, leflunomide may provide a therapeutic potential for human cerebral vasospasm induced by SAH.

Background and Purpose: The study investigated whether eugenosedin-A, a 5-hydroxytryptamine and alpha/beta adrenoceptor antagonist, enhanced delayed-rectifier potassium (K(DR))- or large-conductance Ca(2+)-activated potassium (BK(Ca))-channel activity in basilar artery myocytes through cyclic AMP/GMP-dependent and -independent protein kinases., Experimental Approach: Cerebral smooth muscle cells (SMCs) were enzymatically dissociated from rat basilar arteries. Conventional whole cell, perforated and inside-out patch-clamp electrophysiology was used to monitor K(+)- and Ca(2+)-channel activities., Key Results: Eugenosedin-A (1 microM) did not affect the K(DR) current but dramatically augmented BK(Ca) channel activity in a concentration-dependent manner. Increased BK(Ca) current was abolished by charybdotoxin (ChTX, 0.1 microM) or iberiotoxin (IbTX, 0.1 microM), but not affected by a small-conductance K(Ca) blocker (apamin, 100 microM). BK(Ca) current activation by eugenosedin-A was significantly inhibited by an adenylate cyclase inhibitor (SQ 22536, 10 microM), a soluble guanylate cyclase inhibitor (ODQ, 10 microM), competitive antagonists of cAMP and cGMP (Rp-cAMP, 100 microM and Rp-cGMP, 100 microM), and cAMP- and cGMP-dependent protein kinase inhibitors (KT5720, 0.3 microM and KT5823, 0.3 microM). Eugenosedin-A reversed the inhibition of BK(Ca) current induced by the protein kinase C activator, phorbol myristyl acetate (PMA, 0.1 microM). Eugenosedin-A also prevented BK(Ca) current inhibition induced by adding PMA, KT5720 and KT5823. Moreover, eugenosedin-A reduced the amplitude of voltage-dependent L-type Ca(2+) current (I(Ca,L)), but without modifying the voltage-dependence of the current., Conclusions and Implications: Eugenosedin-A enhanced BK(Ca) currents by stimulating the activity of cyclic nucleotide-dependent protein kinases. Physiologically, this activation would result in the closure of voltage-dependent calcium channels and thereby relax cerebral SMCs.

Background: Angiotensin II (Ang) has been shown to induce expression of transforming growth factor-beta1 (TGF-beta1) in cardiovascular cells in vitro, but the regulation of TGF-beta1 by Ang has not been shown in cerebral vessels in vivo. Here, we tested the hypothesis that Ang promotes proliferative and fibrogenic responses in cerebral vessels through autocrine production and signaling of TGF-beta1 by vascular smooth muscle cells (VSMC)., Methods: Rats were implanted with miniosmotic pumps that delivered a low dose of Ang (9 microg/kg/h subcutaneously for 4 to 28 days). To test for autocrine production and signaling of TGF-beta1 by VSMC, we suppressed TGF-beta1 gene expression in VSMC by infusing antisense oligodeoxynucleotide (AS-ODN) versus sense oligodeoxynucleotide (S-ODN) into the cisterna magna., Results: Systemic infusion of Ang for 28 days caused upregulation of proliferative cell nuclear antigen (PCNA) and of collagen type I in endothelium and VSMC of basilar arteries, with these changes observed as early as day 4, before the onset of hypertension. Also by day 4, significant increases in expression of TGF-beta1, TGF-beta receptors I and II, and phospho-Smad3 were observed in endothelial and VSMC layers, but plasma levels of TGF-beta1 were unchanged. With AS-ODN, but not S-ODN, TGF-beta1 was significantly reduced in VSMC but not in endothelial layers of the basilar artery, and PCNA and collagen upregulation in VSMC were essentially eliminated., Conclusions: Autocrine TGF-beta1 signaling in VSMC is required for Ang-induced proliferative and fibrogenic responses in cerebral vessels in vivo.

Nuclear factor-kappaB (NF-kappaB) plays a key role in inflammation, which is involved in the development of cerebral vasospasm after subarachnoid hemorrhage (SAH). In the present study, we assessed the potential role of NF-kappaB in regulation of cerebral vasospasm. Nuclear factor-kappaB DNA-binding activity was measured in cultured vascular smooth muscle cells (VSMCs) treated with hemolysate and pyrrolidine dithiocarbamate (PDTC, 80 micromol/L), an inhibitor of NF-kappaB. Forty-two rabbits were divided into three groups: control, SAH, and PDTC groups (n=14 for each group). The caliber of the basilar artery was evaluated. Nuclear factor-kappaB DNA-binding activity and the gene expression levels of cytokines and adhesion molecules in the basilar artery were measured. Immunohistochemical study was performed to assess the expression and localization of tumor necrosis factor (TNF)-alpha, intercellular adhesion molecule (ICAM)-1, and myeloperoxidase (MPO). It was observed that NF-kappaB DNA-binding activity was significantly increased by treatment with hemolysate in cultured VSCMs, but this increase was suppressed by pretreatment with PDTC. Severe vasospasm was observed in the SAH group, which was attenuated in the PDTC group. Subarachnoid hemorrhage could induce increases of NF-kappaB DNA-binding activity and the gene expression levels of TNF-alpha, interleukin (IL)-1 beta, ICAM-1, and vascular cell adhesion molecule (VCAM)-1, which were reduced in the PDTC group. Immunohistochemical study demonstrated that the expression levels of TNF-alpha, ICAM-1, and MPO were all increased in the SAH group, but these increases were attenuated in the PDTC group. Our results suggest that NF-kappaB is activated in the arterial wall after SAH, which potentially leads to vasospasm development through induction of inflammatory response.

Introduction: Intracellular calcium concentration ([Ca(2+)](i)) modifications in endothelial and smooth muscle cells represent a key element in the pathogenesis of cerebral artery vasospasm. Therefore, the present study documented potential application of confocal laser microscopy in the determination of contractile and [Ca(2+)](i) responses in basilar artery., Methods: Experiments were performed on the rat isolated basilar artery. Changes in [Ca(2+)](i) were determined by ratiometry involving Fluo-4/AM and Fura Red/AM. Contractile function was calculated from the change in fluorescent area by Fluo-4/AM., Results: KCl (50 mM) elicited an increase in [Ca(2+)](i) and contraction in basilar artery; moreover, nearly well maintained responses were evident for at least 120 min following the first application. 10 microM 5-hydroxytryptamine (5-HT), 10 microM alpha,beta-methyleneadenosine 5'-triphosphate (alpha,beta-meATP) and 10 nM vasopressin (VP) also induced increases in [Ca(2+)](i) and contraction dose-dependently. Additionally, 10 microM acetylcholine elicited a transient [Ca(2+)](i) decrease and sustained relaxation. In individual cells, rhythmical changes in [Ca(2+)](i) were observed after 10 microM 5-HT. VP (10 nM) evoked modest Ca(2+) oscillation in individual cells; however, Ca(2+) oscillation was not detectable with 10 microM alpha,beta-meATP., Discussion: These results indicate that this method offers reproducibility and quantifiable effects. Imaging technology may therefore be applied to the estimation of [Ca(2+)](i) responses at the tissue level as well as at the level of the individual cell. Thus, confocal laser microscopy is a suitable tool for estimation of small artery function.

Object: The key role in the development of cerebral vasospasm after subarachnoid hemorrhage (SAH) is increasingly assigned to endothelin (ET)-1. Constriction of the cerebrovasculature by ET-1 is mainly mediated by the ET(A) receptor but is putatively altered during the development of cerebral vasospasm. Therefore, the aim in the present study was to characterize these alterations, with the emphasis on the ET(A) receptor., Methods: Cerebral vasospasm was induced using the rat double-hemorrhage model and proven by perfusion weighted magnetic resonance imaging. Rats were killed on Day 5 after SAH, and immunohistochemical staining for ET(A), receptors was performed. The isometric force of basilar artery ring segments with (E+, control group) and without (E-, SAH group) endothelial function was measured. Concentration effect curves (CECs) for ET-1 were constructed by cumulative application in the absence and presence of the selective ET(A) receptor antagonist clazosentan (10(-8) or 10(-7) M)., Results: The CEC for E+ segments was significantly shifted to the left after SAH by a factor of 3.7, whereas maximum contraction was unchanged. In E- segments, the CECs were not shifted during cerebral vasospasm but the maximum contraction was significantly enhanced. The inhibitory potency of clazosentan yielded a pA2 value of 8.6 +/- 0.2. Immunohistochemical staining of the smooth-muscle layer showed no significant increase of ET(A) receptor expression, but positive staining occurred in the endothelial space after SAH., Conclusions: The present data indicate an enhanced contractile effect of the smooth-muscle ET(A) receptors in cases of cerebral vasospasm. The inhibitory potency of clazosentan on this contraction is increased. Furthermore, some evidence for an ET(A) receptor and an endothelium-dependent vasoactive effect after SAH is provided.

It is known that myogenic reactivity is a fundamental determinant of the relative constancy of blood flow through the cerebral artery. It is also known that acute alteration of pH significantly affects the cerebral circulation and, therefore, we investigated the effect of mechanism of action of intracellular acidosis on myogenic tone in rabbit basilar artery. Myogenic tone was developed by imposed stretch of basilar artery and intracellular acidosis induced by the bath application of 20 mmol/L sodium acetate. Sodium acetate caused a biphasic increase in myogenic tone. The initial component reached a peak quickly and then fell slowly to a lower steady-state significantly above basal tone. The sodium acetate-induced increase in myogenic tone was completely inhibited by elimination of external Ca2+, or treatment of nifedipine, but not with gadolinium or NPPB. TEA (5 mmol/L) and iberiotoxin (100 nmol/L) inhibited the sodium acetate-induced increase in myogenic tone. In inside-out patch-clamp recordings, decreasing pH of the mock intracellular solution from 7.4 to 6.9 markedly inhibited BKCa currents. Several inhibitors involved in Ca2+ sensitization pathways, 10(-6) mol/L Y-27632, 5 x 10(-7) mol/L calphostin C and 10(-5) mol/L PD98059 had no effect on the sodium acetate-induced increase in myogenic tone. These results suggest that intracellular acidosis increases stretch-induced myogenic tone in rabbit basilar artery. Furthermore, voltage-dependent Ca2+ influx plays a key role in intracellular acidosis-induced increase in myogenic tone and may be mediated, at least in part, by inhibition of BKCa.

Objectives: Increased calcium sensitization mediated by Rho/Rho-kinase may be important in the pathogenesis of cerebral vasospasm. The effects of a highly selective Rho-kinase inhibitor, Y-27632, were investigated on spasmogen-induced contractions of canine basilar artery., Methods: Typical spasmogenic substances present after subarachnoid hemorrhage (SAH), including prostaglandin F2a (PGF2a), 12-deoxyphorbol 13-isobutyrate (DPB), sphingosylpho-sphorylcholine (SPC) and high K+, were used in the study. Isometric tension was recorded in canine basilar artery rings in vitro. Intracellular calcium concentration ([Ca2+]i) and contraction force were measured simultaneously in fura-2-loaded canine basilar artery strips. The myosin light chain (MLC) phosphorylation levels were measured by glycerol gel electrophoresis followed by Western blotting., Results: Isometric tension recording revealed that the Rho-kinase inhibitor, Y-27632, dose-dependently inhibited vasocontraction induced by PGF2a and SPC, but not that induced by DPB. Simultaneous recordings of [Ca2+]i and tension revealed that the vasorelaxing effect of Y-27632 was not associated with changes in [Ca2+]i, suggesting that Y-27632 may inhibit calcium sensitization. Vasocontraction induced by DPB was not inhibited by Y-27632, but was inhibited by staurosporine. Phosphorylation of MLC was increased by PGF2a and SPC, and significantly inhibited by Y-27632, whereas such phosphorylation was increased by DPB, but not significantly inhibited by Y-27632., Discussion: Several spasmogenic mediators released after SAH may cause vasospasm through Rho-kinase-mediated increase in calcium sensitization. Rho-kinase inhibitors, including Y-27632, may be effective for the prevention of cerebral vasospasm after SAH.

To study the contractile responses of the human basilar artery to 5-hydroxytryptamine (5-HT), sumatriptan, zolmitriptan and naratriptan, and to characterize the 5-HT receptor subtypes involved on those responses, human basilar artery rings were prepared for isometric contraction, protein isolation and Western blotting analysis. Concentration-response (CR) curves were made for all agonists in the absence or in the presence of selective antagonists at 5-HT1B (cyanopindolol), 5-HT1D (BRL 15,572) and 5-HT2 (ketanserin) receptors. We also used anti-5-HT1B and 5-HT1D receptor antibodies to search for the expression of protein of these receptor subtypes. From the CR curves, the relative intrinsic activity and potency of these agonists were determined. The ranking order for the intrinsic activity was 5-HT > or = sumatriptan > zolmitriptan > or = naratriptan, whereas that for the potency was zolmitriptan > or = 5-HT > or = sumatriptan > naratriptan. Our results also show that the human basilar artery seems to have a mixed population of 5-HT1B/1D receptors mediating the contractile response to triptans, which is also suggested by the expression of both receptor subtypes. There is also a population of 5-HT2 receptors for which the antimigraine drugs used have no apparent affinity. From this study, one can conclude that the second generation triptans have lower contractile capacity than sumatriptan, suggesting that they have a better cerebrovascular safety profile.

Employing microfluorometric system and patch clamp technique in rabbit basilar arterial myocytes, regulation mechanisms of vascular excitability were investigated by applying intracellular pH (pH(i)) changers such as sodium acetate (SA) and NH(4)Cl. Applications of caffeine produced transient phasic contractions in a reversible manner. These caffeine-induced contractions were significantly enhanced by SA and suppressed by NH(4)Cl. Intracellular Ca(2+) concentration ([Ca(2+)](i)) was monitored in a single isolated myocyte and based the ratio of fluorescence using Fura-2 AM (R (340/380)). SA (20 mM) increased and NH(4)Cl (20 mM) decreased R (340/380) by 0.2 +/- 0.03 and 0.1 +/- 0.02, respectively, in a reversible manner. Caffeine (10 mM) transiently increased R (340/380) by 0.9 +/- 0.07, and the ratio increment was significantly enhanced by SA and suppressed by NH(4)Cl, implying that SA and NH(4)Cl may affect [Ca(2+)](i) (p < 0.05). Accordingly, we studied the effects of SA and NH(4)Cl on Ca(2+)-activated K(+) current (IK(Ca)) under patch clamp technique. Caffeine produced transient outward current at holding potential (V (h)) of 0 mV, caffeine induced transient outward K(+) current, and the spontaneous transient outward currents were significantly enhanced by SA and suppressed by NH(4)Cl. In addition, IK(Ca) was significantly increased by acidotic condition when pH(i) was lowered by altering the NH(4)Cl gradient across the cell membrane. Finally, the effects of SA and NH(4)Cl on the membrane excitability and basal tension were studied: Under current clamp mode, resting membrane potential (RMP) was -28 +/- 2.3 mV in a single cell level and was depolarized by 13 +/- 2.4 mV with 2 mM tetraethylammonium (TEA). SA hyperpolarized and NH(4)Cl depolarized RMP by 10 +/- 1.9 and 16 +/- 4.7 mV, respectively. SA-induced hyperpolarization and relaxation of basal tension was significantly inhibited by TEA. These results suggest that SA and NH(4)Cl might regulate vascular tone by altering membrane excitability through modulation of [Ca(2+)](i) and Ca(2+)-activated K channels in rabbit basilar artery.

Basilar-type migraine (BM) has been recognised in the revised International Classification of Headache Disorders as a distinct clinical entity (subtype of migraine with aura), characterised by disturbing migraine aura clearly originating from the brainstem or from both hemispheres simultaneously affected. It differs from familial and sporadic hemiplegic migraines by the absence of motor deficit. Lamotrigine has been shown to be effective in preventing migraine aura symptoms in typical aura and in some cases of BM. We tried lamotrigine in three female cases of BM.

Background and Purpose: A motif of 11 consecutive arginines (11R) is reported to be one of the most effective protein transduction domains for introducing proteins into the cell membrane. We therefore examined the transduction efficiency of 11R in cerebral arteries., Methods: Basilar arteries (BAs) obtained from rats were incubated with either 11R-enhanced green fluorescent protein (11R-EGFP) or EGFP without 11R. After incubation, expression of 11R-EGFP or EGFP in BA serial sections was observed by fluorescence microscope. In an additional in vivo experiment, 11R-EGFP or EGFP was injected into the cisterna magna with or without subarachnoid hemorrhage. The 11R-EGFP or EGFP was injected just after the autologous blood injection, and then the expression of 11R-EGFP or EGFP in BA sections was also observed by fluorescence microscope., Results: The 11R-EGFP signal was much stronger than that of EGFP in all layers of the rat BA, in both in vivo and ex vivo experiments. Moreover, the 11R-EGFP was transduced into the BA immediately (2 hours after the injection). Interestingly, 11R-fused fluorescent protein was transduced especially into the tunica media of the BA., Conclusions: The 11R-fused fluorescent protein effectively penetrates into all layers of the rat BA, especially into the tunica media. This is the first study to our knowledge to demonstrate the successful transduction of a protein transduction domain fused protein into the cerebral arteries.

Background and Purpose: Acute basilar artery occlusion portends high risk of stroke and death. Thrombolysis or endovascular therapy has been limited to patients who present within hours of symptom onset. Without recanalization, acute basilar artery occlusion almost always results in death or severe disability., Summary of Case: We report a case of basilar artery occlusion and successful endovascular recanalization 80 days after symptom onset., Conclusions: Endovascular therapy can be feasible and safe for symptomatic basilar artery occlusion at chronic stage.

Background: Inflammatory processes may play a pivotal role in the pathogenesis of cerebrovascular injury in salt-loaded, stroke-prone, spontaneously hypertensive rats (SHRSP). Thromboxane A2 (TP) receptor stimulation by 8-iso-prostaglandin F2alpha (8-iso-PGF2alpha) is involved in the process of vascular inflammation., Objective: In the present study, we examined the involvement of TP receptor in the development of cerebrovascular damage in salt-loaded SHRSP., Methods: Nine-week-old SHRSP were fed a 0.4% NaCl or a 4% NaCl diet with or without ONO-8809 treatment (a TP receptor antagonist) for 5 weeks. Blood pressure, mortality, and the parameters of cerebrovascular inflammation and damage were compared between the groups. Moreover, we examined the effect of 8-iso-PGF2alpha infusion on cerebrovascular injury of SHRSP., Results: High salt intake in SHRSP significantly increased blood-brain barrier impairment and early mortality, which were suppressed by ONO-8809 treatment independent of changes in blood pressure. Salt loading also significantly increased superoxide production in basilar arteries of SHRSP, which was suppressed by ONO-8809 treatment. Macrophage accumulation and matrix metalloproteinase-9 (MMP-9) activity in the stroke-negative area in the contralateral cerebral cortex to the stroke lesion of salt-loaded SHRSP and 8-iso-PGF2alpha-treated SHRSP were significantly reduced by ONO-8809 treatment. The ONO-8809 treatment prevented thinning of the vessel layer in cerebral arterioles of salt-loaded SHRSP and 8-iso-PGF2alpha-treated SHRSP., Conclusions: These results suggest that TP receptor stimulation by 8-iso-PGF2alpha may involve salt loading-induced stroke through activation of cerebrovascular inflammation and damage.

Evidence that inflammatory and immune mechanisms may have a critical role in the development of vasospasm after subarachnoid hemorrhage is accumulating. We examined, therefore, whether induction of immunological tolerance to the adhesion molecule that is uniquely expressed on activated endothelium, E-selectin, could inhibit the vasospasm provoked by subarachnoid blood in a rat subarachnoid hemorrhage model. We found that intranasal instillation of E-selectin every other day for 10 days on a mucosal tolerization schedule suppressed delayed type hypersensitivity to E-selectin confirming tolerance to that molecule and markedly suppressed basilar artery spasm after subarachnoid hemorrhage. The results of this proof-of-concept study suggest that agents that can mimic the local effects of the mediators of mucosal tolerance could have therapeutic potential for the management of post-subarachnoid hemorrhage vasospasm.

The vascular resting tone of the porcine basilar artery appears to be mostly maintained by a balance between spontaneously released nitric oxide (NO) from endothelial cells and thromboxane (TX) A(2) from endothelial and smooth muscle cells. However the precise role of the interaction between the above two substances in the control of vascular tone is unclear. We attempted to clarify the interaction between NO and TXA(2) using cultured porcine basilar arterial endothelial cells. The cultured endothelial cells produced NO spontaneously, while TXB(2) (a stable metabolite of TXA(2)) production remained below the detection limit. Ibuprofen (a COX inhibitor) and ozagrel (a TXA(2) synthetase inhibitor) significantly increased the spontaneous production of NO, which was not affected by 1400W (an iNOS inhibitor). l-Nitro arginine (a NOS inhibitor) significantly induced TXB(2) production. These results suggest that NO may inhibit COX or TXA(2) synthetase, and that therefore inhibition of NOS might disinhibit COX or TXA(2) synthetase, subsequently inducing TXA(2) production. On the other hand, as TXA(2) and other contractility-related prostaglandin(s) may inhibit NOS, therefore the inhibition of COX or TXA(2) synthetase might disinhibit NOS, and then increase the spontaneous production of NO in porcine basilar arterial endothelial cells.

The poor prognosis for recovery of basilar artery thrombosis has led to the adoption at many institutions of intra-arterial thrombolysis as part of clinical care. However, because neither randomized clinical trials nor observational data provide evidence for treatment efficacy and there are substantial risks and costs associated with this procedure, this treatment should only be performed in the context of a randomized, controlled clinical trial subject to appropriate Institutional Review Board review and independent safety monitoring.

Objectives: To evaluate the effect of estrogen replacement therapy or soy isoflavones supplement on endothelium-dependent relaxation in vitro and gene expression of endothelial nitric oxide synthase (eNOS) in cerebral arteries in a rabbit model of human hypercholesterolemia., Study Design: Thirty-six female ovariectomized Watanabe heritable hyperlipidemic (WHHL) rabbits were randomised to treatment with 17beta-estradiol (17beta-E(2)), SoyLife 150 or control for 16 weeks. Ring segments of basilar artery (BA) and posterior cerebral artery (PCA) were mounted in myographs for isometric tension recordings. Concentration response curves to carbamylcholine chloride, sodium nitroprusside (SNP) and l-NAME were evaluated after precontraction with potassium. Total RNA was extracted, reverse transcribed and eNOS quantitated by real-time polymerase chain reaction (real-time PCR)., Results: Plasma cholesterol was significantly higher at termination in the SoyLife group (P<0.0001), whereas low-density lipoprotein (LDL) cholesterol was comparable in all treatment groups. Neither treatment influenced the endothelium-dependent responses to carbamylcholine chloride or l-NAME or the endothelium-independent response to SNP in any of the arteries. Correspondingly, eNOS mRNA was similarly expressed in all treatment groups in both arteries., Conclusions: Improvement of cerebral endothelial function by estrogen or soy isoflavones in ovariectomized WHHL rabbits is not supported by the present data. The findings may be unique to the WHHL rabbit in which the hypocholesterolemic effect of estrogens mediated by upregulation of liver LDL receptors is excluded.

We investigated if the magnitude of myogenic tone in the basilar artery of SHR differs from that in WKY and, if so, whether RhoA- or PKC-dependent mechanisms were involved. Myogenic tone was developed in response to stretch. Stretch-induced myogenic contraction was significantly greater in the SHR than WKY in the presence of external Ca(2+). However, in the absence of external Ca(2+), stretch did not evoke a myogenic tone. The [Ca(2+)](i)-induced contraction was larger in SHR than WKY and the [Ca(2+)](i)-force curve was significantly shifted to the left in SHR compared to WKY. Y-27632 significantly inhibited stretch-induced myogenic tone, but the inhibitory effect was larger in the SHR than WKY. However, PKC inhibitors had no significant effect on the myogenic tone. RhoA and PKCepsilon were expressed at higher levels in the SHR compared to the WKY. RhoA and PKCalpha translocated from the cytosol to the cell membrane in response to stretch in both animals, but PKCepsilon was translocated only in SHR. Our results strongly suggest that stretch-induced myogenic tone is enhanced in SHR, and the activation of RhoA/Rho kinase plays an important role in the enhanced myogenic tone in SHR.

The pathogenesis of cerebral ischaemia after subarachnoid haemorrhage (SAH) still remains elusive. The purpose of the present study was to examine whether specific protein kinas C (PKC) inhibition in rats could alter the transcriptional SAH induced Endothelin (ET) type B and 5-hydroxytryptamine type 1B (5-HT(1B)) receptor upregulation and prevent the associated cerebral blood flow (CBF) reduction. The PKC inhibitor RO-31-7549 or vehicle was injected intracisternally after the induced SAH in rats (n=3 to 10 in each groups for each method). The involvement of the PKC isoforms was investigated with Western blot; only PKCdelta and PKCalpha subtypes were increased after SAH RO-31-7549 treatment abolished this. At 2 days after the SAH basilar and middle cerebral arteries were harvested and the contractile response to endothelin-1 (ET-1; ET(A) and ET(B) receptor agonist) and 5-carboxamidotryptamine (5-CT; 5-HT(1) receptor agonist) were investigated with a myograph. The contractile responses to ET-1 and 5-CT were increased (P<0.05) after SAH compared with sham operated rats. In parallel, the ET(B) and 5-HT(1B) receptor mRNA and protein expression were significantly elevated after SAH, as analysed by quantitative real-time polymerase chain reaction and immunohistochemistry, respectively. Administration of RO-31-7549 prevented the upregulated contraction elicited by application of ET-1 and 5-CT in cerebral arteries and kept the ET(B) and 5-HT(1B) receptor mRNA and protein levels at pre-SAH levels. Regional and global CBF evaluated by an autoradiographic technique were reduced by 60%+/-4% after SAH (P<0.05) and prevented by treatment with RO-31-7549. Our study suggests that PKC plays an important role in the pathogenesis of cerebral ischaemia after SAH.

ATP-sensitive potassium (K(ATP)) channels play an important role in the regulation of cerebral vascular tone. In vitro studies using synthetic K(ATP) channel openers suggest that the pharmacological profiles differ between rat basilar arteries and rat middle cerebral arteries. To address this issue, we studied the possible involvement of endothelial K(ATP) channels by pressurized arteriography after luminal administration of synthetic K(ATP) channel openers to rat basilar and middle cerebral arteries. Furthermore, we examined the mRNA and protein expression profile of K(ATP) channels to rat basilar and middle cerebral arteries using quantitative real-time PCR (Polymerase Chain Reaction) and Western blotting, respectively. In the perfusion system, we found no significant responses after luminal application of three K(ATP) channel openers to rat basilar and middle cerebral arteries. In contrast, abluminal application caused a concentration-dependent dilatation of both arteries, that was more potent in basilar than in middle cerebral arteries. Quantitative real-time PCR detected the presence of mRNA transcripts of the K(ATP) channel subunits Kir6.1, Kir6.2, SUR1 and SUR2B, while SUR2A mRNA was barely detected in both rat basilar and middle cerebral arteries. Of the five mRNAs, the expression levels of Kir6.1 and SUR2B transcripts were predominant in both rat basilar and middle cerebral arteries. Western blotting detected the presence of Kir6.1, Kir6.2, SUR1 and SUR2B proteins in both arteries. Densitometric measurements of the Western blot signals further showed higher expression levels of Kir6.1 and SUR2B proteins in rat middle cerebral arteries than was found in rat basilar arteries. In conclusion, our in vitro pharmacological studies showed no evidence for functional endothelial K(ATP) channels in either artery. Furthermore, the results indicate that Kir6.1/SUR2B is the major K(ATP) channel complex in rat basilar and middle cerebral arteries.

Objective: One of the phosphodiesterase isoenzymes, Type V (PDE V), specifically hydrolyzes cyclic guanosine monophosphate to cause vasoconstriction. This study analyses the effect of PDE V inhibition with sildenafil citrate (SC) on cerebral vasospasm and its effect on apoptotic changes of the vascular endothelium., Methods: Twenty-four rabbits were divided into four groups. The first group was composed of sham-surgery animals. The second group was the subarachnoid hemorrhage (SAH) group, in which cerebral vasospasm was induced. In the third group, sham-surgery rabbits were treated with SC. In the fourth group, animals were treated with SC after SAH. SC was administered for 48 hours, 0.7 mg/kg, three times per day in Groups 3 and 4. Basilar artery lumen circumferences were measured in all groups by computerized image analysis. The terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling (TUNEL) method was used to evaluate the rate of apoptosis between SAH and SC-treated SAH groups. Results were compared by analysis of variance and paired t tests, and P values less than 0.05 were considered significant., Results: Basilar artery circumferences between groups were significantly different (P < 0.001). SC (0.7 mg/kg, three times per d) significantly dilated the basilar arteries in both the sham-surgery group (2370 +/- 233 microm; P = 0.039) and the SAH group (2142 +/- 195 microm; P = 0.006) after 48 hours of treatment. The TUNEL method for apoptosis revealed that actual numbers of the apoptotic endothelial cells per cross section after SAH in the control (no treatment) (73 +/- 2) and SC-treated (0.7 mg/kg) groups(76 +/- 3) were not significantly different (P > 0.05)., Conclusion: The vasodilatory effect of SC was observed to be significant on normal cerebral vessels and after SAH-induced vasospasm. SC did not prevent apoptosis of the endothelium in our study, which suggests that prevention of apoptosis is not necessary in the treatment of cerebral vasospasm.

Objective: Leukocyte-endothelial cell interactions appear to play a role in the development of vasospasm after SAH. Using a purely inflammatory protein, LPS, we evaluated the effect of inflammation on the development of chronic vasospasm in the absence of blood and compared it to SAH-induced vasospasm in rabbits., Methods: Lipopolysaccharide was incorporated into EVAc polymers to produce 20% LPS/EVAc polymers (wt/wt). Rabbits (n = 23) were randomized to 4 experimental groups: (1) empty polymer (n = 6), (2) SAH (n = 5), (3) 0.7 mg/kg polymeric LPS dose (n = 6), and (4) 1.4 mg/kg polymeric LPS dose (n = 6). Blood and polymers were inserted into the cisterna magna. The rabbits were killed 3 days postoperatively, and the basilar arteries were harvested for morphometric analysis. Clinical response and lumen patencies were analyzed using ANOVA and a post hoc Newman-Keuls Multiple Comparisons test., Results: Significant narrowing of the basilar artery was observed by insertion of 20% LPS/EVAc polymers into the subarachnoid space at a polymeric dose of 1.4 mg/kg (actual dose, 66 microg kg(-1) d(-1)) (75.4% +/- 4.2%; P < .01) and by SAH (80.3% +/- 8.1%; P < .01) as compared with the empty polymer group. A trend toward narrowing was observed in the 0.7 mg/kg polymeric LPS dose group (actual dose, 33 microg kg(-1) d(-1)) (85.2% +/- 2.6%; P > .05). Symptoms associated with SAH were noted in 50% of the rabbits in the 0.7 mg/kg LPS group and in 100% of rabbits in the 1.4 mg/kg LPS group., Conclusion: Controlled release of LPS into the subarachnoid space of rabbits produced chronic vasospasm in a dose-dependent manner. At a polymeric dose of 1.4 mg/kg, LPS-induced vasospasm was equivalent to that induced by SAH. This suggests that LPS and SAH may induce vasospasm through similar mechanisms and provides further evidence that inflammation plays a central role in the etiology of chronic vasospasm.

20-Hydroxyeicosatetraenoic acid (20-HETE), an arachidonic acid (AA) metabolite synthesized by cytochrome P-450 omega-oxidases, is reported to produce vasoconstriction in the cerebral circulation. However, we find that like 14,15-epoxyeicosatrienoic acid (14,15-EET), 20-HETE produces dilation of mouse basilar artery preconstricted with U-46619 in vitro. Indomethacin inhibited the vasodilation produced by 20-HETE but not by 14,15-EET, suggesting a cyclooxygenase (COX)-dependent mechanism. Metabolic studies indicated several mechanisms that may play a role in this process. Mouse brain endothelial cells (MBEC) converted 20-HETE to 20-OH-PGE(2), which was as potent as PGE(2) in dilating the basilar artery. 20-HETE also stimulated AA release and PGE(2) and 6-keto-PGF(1alpha) production in MBEC. Furthermore, the basilar artery converted 20-HETE to 20-COOH-AA, which also produced COX-dependent dilation of the basilar artery. 20-COOH-AA increased AA release and PGE(2) and 6-keto-PGF(1alpha) production by the MBEC, but to a lesser extent than 20-HETE. Whereas the conversion of 20-HETE to 20-OH-PGE(2) and production of endogenous prostaglandins probably are primarily responsible for vasodilation, the production of 20-COOH-AA also may contribute to this process.

Object: The object of this study was to determine whether the combination of cyclosporine and simvastatin could ameliorate cerebral vasospasm after subarachnoid hemorrhage (SAH) in a canine model to a greater extent than simvastatin alone., Methods: Animals were assigned to one of three groups: control (five dogs), simvastatin alone (four), or simvastatin and cyclosporine (four). A double SAH model was used. Baseline basilar artery (BA) angiograms were obtained. These were repeated at Days 3, 7, and 10. Measurement of the BA diameter was performed. Decreased BA diameter was seen on Day 3 in the control and simvastatin/cyclosporine group. A return to baseline diameters was seen by Day 7. An increase from baseline diameter was seen in the simvastatin group at Day 10., Conclusions: Cyclosporine may interfere with the vasodilatory effects of simvastatin. Vasodilation greater than baseline is seen at Day 10 in the simvastatin group. The combination of simvastatin and cyclosporine does not ameliorate cerebral vasospasm in a canine model to a greater extent than simvastatin alone.

The effects of angiotensin II type 1 receptor blockers (ARBs) on cerebral blood flow (CBF) autoregulation have not been fully clarified. Thus, we examined the acute effect of valsartan, the most selective ARB, on CBF autoregulation in spontaneously hypertensive rats. Intravenous administration of valsartan (0.3 mg/kg) reduced the mean arterial pressure (MAP) from 184+/-5 (mean+/-SEM) to 174+/-5 mmHg (p<0.001) without affecting CBF as measured by laser-Doppler flowmetry. The lower limit of CBF autoregulation (the MAP at which the CBF was 80% of the baseline value) in the valsartan-treated group (122+/-3 mmHg) was significantly lower than that in the control group (135+/-4 mmHg, p<0.05). Reverse transcribed-polymerase chain reaction and immunohistochemical staining demonstrated that both angiotensin II type 2 receptors and angiotensin II type 1 receptors (AT1Rs) were expressed in endothelial and smooth muscle cells of the rat cerebral arteries. These results suggest that specific inhibition of AT1Rs in the cerebral circulation causes the leftward shift of the lower limit of autoregulation.

Reactive oxygen species (ROS) are a diverse family of molecules generated by all cells. ROS may serve as important cell-signalling molecules in the cerebral circulation. Indeed, in contrast to systemic arteries, major products of superoxide metabolism, including hydrogen peroxide, are powerful cerebral vasodilators, raising the possibility that ROS represent important molecules for increasing local cerebral blood flow. Two major determinants of the overall effects of ROS on cerebrovascular tone are the rate of production of the parent molecule, superoxide, and its rate of metabolism by superoxide dismutases. Although the major enzymatic source of ROS in cerebral arteries has not been clarified, nicotinamide adenine dinucleotide phosphate, reduced form (NADPH)-oxidases, along with cyclooxygenases and lipoxygenases, are probably the primary sources. In cerebral arteries, activation of NADPH-oxidase elicits both an increase in superoxide production and vasodilatation. The identity of the ROS molecule responsible for the vasodilator effects may be hydrogen peroxide, generated from the dismutation of superoxide. NADPH-oxidase activity and function appears to be profoundly greater in cerebral versus systemic arteries. Furthermore, NADPH-oxidase-derived ROS partly contribute to flow-dependent dilatation and may offset angiotensin II-induced constriction of cerebral arteries, consistent with the hypothesis that NADPH-oxidase-derived ROS may play a physiologic role in the control of cerebrovascular tone.