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Nitric oxide (NO) is involved in neuronal modifications, and overproduction of NO contributes to memory deficits after acute hypobaric hypoxia-reoxygenation. This study investigated the ability of the iNOS inhibitor 1400W to counteract spatial memory deficits following acute hypobaric hypoxia-reoxygenation, and to affect expression of NOS, NO, 3-NT and MDA production, and apoptosis in rat cerebral cortex. We also used primary rat microglia to investigate the effect of 1400W on expression of NOS, NO, 3-NT and MDA production, and apoptosis. Acute hypobaric hypoxia-reoxygenation impaired spatial memory, and was accompanied by activated microglia, increased iNOS expression, NO, 3-NT and MDA production, and neuronal cell apoptosis in rat cerebral cortex one day post-reoxygenation. 1400W treatment inhibited iNOS expression without affecting nNOS or eNOS. 1400W also reduced NO, 3-NT and MDA production, and prevented neuronal cell apoptosis in cerebral cortex, in addition to reversing spatial memory impairment after acute hypobaric hypoxia-reoxygenation. Hypoxia-reoxygenation activated primary microglia, and increased iNOS and nNOS expression, NO, 3-NT, and MDA production, and apoptosis. Treatment with 1400W inhibited iNOS expression without affecting nNOS, reduced NO, 3-NT and MDA production, and prevented apoptosis in primary microglia. Based on the above findings, we concluded that the highly selective iNOS inhibitor 1400W inhibited iNOS induction in microglial cells, and reduced generation of NO, thereby mitigating oxidative stress and neuronal cell apoptosis in the rat cerebral cortex, and improving the spatial memory dysfunction caused by acute hypobaric hypoxia-reoxygenation.

To observe the effect of oxidized low density lipoprotein (OxLDL) on arterial endothelial cells apoptosis in vivo, we established a model in which Sprague-Dawley rats were given intraperitoneal and intravenous injection of unmodified LDL (8 mg/kg every day) via the tail vein. Seven days after the injection, the aortic endothelial cells specimens were prepared by an en face preparation of rat aorta. The apoptotic cells were identified and counted by in situ nick and labelling (TUNEL) method and light microscopy. The numbers of the apoptotic cells were 12.52 +/- 4.71/field in the intraperitoneal injection control group, 11.41 +/- 2.94/field in the intravenous injection control group, 22.98 +/- 8.01/field in the intraperitoneal injection LDL group and 103.8 +/- 11.5/field in the intravenous injection LDL group, respectively. The difference was significant between injection LDL group and control (P0.01), and the difference was also significant between two LDL injection groups (P0.01). These findings suggest that injection of LDL can induce apoptosis in arterial endothelial cells and the effect is especially significant with intravenous injection LDL. After injection, oxidative modification of LDL may occur in local arteries and causes injury to the endothelial cells.

The model of SD rats ligated at the proximate left anterior descend (LAD) of coronary was used. The number and dissociation constant of beta receptor were studied by using receptor autoradiography to observe the changes in beta receptor and the effects of Radix Ginseng Rubra on cAMP in experimental ischemic myocardium. The result showed that the number of binding site in simple ligation group (Bmax = 0.279) was obviously higher than that in sham operation group (Bmax = 0.093) and the dissociation constant of simple ligation group (Kd = 12. 431) was higher than that of sham operation group (kd = 1.319). There was a significant difference between the two groups (P0.05). It proved that the number of beta receptor was increased and the activity was elevated in myocardial cell membranes after ligation of LAD. The myocardial cAMP level in simple ligation group [(1293.96 +/- 519.36) x 10(-3) nmol/g] was much higher than that in sham operation group [(774.44 +/- 210.55) x 10(-3) nmol/g]; but the level of cAMP in ligation group after receiving Radix Ginseng Rubra treatment (805.02 +/- 362.48 pm/g) was obviously lower than that in simple ligation group (P0.01), which was close to the result of sham operation. The results indicated that Radix Ginseng Rubra could decrease the cAMP level in ischemic myocardium.

The effect of anti-hypertensive drug amlodipine on regression of cardiovascular hypertrophy due to hypertension was studied by using cultured smooth muscle cells derived from arteries of spontaneously hypertensive rats (SHR) and measuring [3H]-TdR and [3H]-Leucine binding. 48 h after adding amlodipine, [3H] -TdR binding in arterial smooth muscle cells from SHRin vitro was reduced by 50. 5 % and [3H]-Leucine binding was reduced by 56. 2 % as compared with neuropeptide Y(NPY)-treated group. However, there was no significant change in cell number. The results showed that amlodipine could effectively inhibit increase of DNA and protein synthesis of vascular smooth muscle cell (VSMC) due to NPY. It indicates that amlodipine is of great significance on regression of genesis and development of cardiovascular hypertrophy due to hypertension.

In order to study the effects of losartan on cardiomyocyte apoptosis following ischemia (0.5 h) and reperfusion (48 h) in vivo and bcl-2 and bax gene expression, TUNEL staining method, immunohistochemistry and in situ hybridization histochemistry (ISHH) were used to monitor the apoptotic cells, mRNA and protein of gene expression, respectively. Image processing system was used to quantitatively dispose the positive metric substance of both immunohistochemistry and ISHH through the average optical density (OD) value. The number of the apoptotic cells were 38 +/- 9 (control group), 0-1 (sham operation group) and 9 +/- 4 (losartan-treated group) in each visual field respectively with the difference among the groups being significant (P0.001). OD values of bcl-2 (ISHH) were 0.07425 +/- 0.02029 (control group), 0.05961 +/- 0.009932 (sham operation group) and 0.07619 +/- 0.01445 (losartan-treated group) respectively, while OD values of bcl-2 (immunohistochemistry) were 0.1374 +/- 0.01367 (control group), 0.08510 +/- 0.01862 (sham operation group) and 0.1252 +/- 0.02064 (losartan-treated group). bcl-2 gene expression was increased significantly in the control group and losartan-treated group as compared with sham operation group (P0.05). OD value of bax (immunohistochemistry) was 09727 +/- 0.02230 (control group), 0.06182 +/- 0.01430 (sham operation group) and 0.06213 +/- 0.01420 (losartan-treated group). bax gene expression was decreased very significantly in losartan-treated group and sham operation group as compared with control group (P0.001). Bcl-2/bax ratio was 1.413 (control group), 1.376 (sham operation group) and 2.016 (losartan-treated group) respectively. The results indicated that losartan might inhibit cardiomyocyte apoptosis following ischemia and reperfusion. The mechanism might be that bax gene expression was inhibited to increase bcl-2/bax ratio.

The effect of ginsenoside Rb1 on cardiomyocyte apoptosis after ischemia (30 min) and reperfusion (6 h) in rats was observed. The ischemia/reperfusion heart model was established by ligating left anterior descending branch of coronary artery in Wistar rats. The apoptotic cardiomyocytes were examined under transmission electron microscopy and counted by in situ nick end labeling (TUNEL) method and light microscopy. Results showed that (1) The apoptotic cardiomyocytes were found in ischemic regions in the ischemia/reperfusion group, but not in the sham-operating group under transmission electron microscopy; (2) The number of apoptotic cells were 134.45 +/- 45.61/field in the ischemia/reperfusion group, 0/field in the sham-operating group and 51.65 +/- 13.71/field in the ginsenoside Rb1-treated group. The differences were significant among the three groups (P0.01). It was concluded that myocardial ischemia-reperfusion could induce cardiomyocyte apoptosis, and ginsenoside Rb1 could significantly inhibit cardiomyocyte apoptosis induced by ischemia-reperfusion in rats, indicating that ginsenoside Rb1 could inhibit cardiomyocyte apoptosis induced by ischemia-reperfusion, thus alleviating ischemia-reperfusion injury.

By ligating the proximate left anterior descend (LAD) of coronary artery and inducing the ventricular fibrillation with electrical stimulation, the preventive effects of electroacupuncture (EA) on ventricular fibrillation were observed. The results showed that the ventricular fibrillation threshold (VFT) of rats with acute ischemic myocardium was raised after acupuncturing some acupoints, which could prevent the occurrence of ventricular fibrillation. Furthermore, the combination of EA and propranolol could enhance the VFT effectively, and they showed a good synergistic effect.

By using receptor autoradiography to observe the distribution and density of receptors, the effects of propranolol, a beta-blocker, on beta-adrenergic receptor of experimental acute myocardial infarction (AMI) were studied. One week after ligation of proximate left anterior descend (LAD) coronary artery, [3H] DHA binding sites were markedly decreased in both infarct region and non-infarct region. After treatment of propranolol (100 micrograms/kg), the [3H] DHA binding sites were obviously increased in the infarct region, and they were further decreased in the non-infarct region. The ratio of [3H] DHA binding sites of the infarct region to non-infarct region was from 0.24 at LAD ligation to 0.87 after propranolol treatment, which was close to 0.97 of control group (sham operation). The results indicated that the propranolol acted directly on myocardial beta- adrenergic through the receptor regulation of the balance of beta-receptors between the infarct region and non-infarct region, and improvement of the myocardial consonation and contraction synergism, thereby protecting the heart affected by AMI.