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In order to investigate the role of nitrative stress in vascular endothelial injury in hyperhomocysteinemia (HHcy), thirty healthy adult female Wistar rats were randomly divided into three groups: control, hyperhomocysteinemia model, and hyperhomocysteinemia with FeTMPyP (peroxynitrite scavenger) treatment. The endothelium-dependent dilatation of thoracic aorta in vitro was determined by response to acetylcholine (ACh). The histological changes in endothelium were assessed by HE staining and scanning electron microscopy (SEM). The expression of 3-nitrotyrosine (NT) in thoracic aorta was demonstrated by immunohistochemistry and immunofluorescence, and the number of circulating endothelial progenitor cells (EPCs) was quantified by flow cytometry. Hyperhomocysteinemia caused significant endothelial injury and dysfunction including vasodilative and histologic changes, associated with higher expression of NT in thoracic aorta. FeTMPyP treatment reversed these injuries significantly. Further, the effect of nitrative stress on cultured EPCs in vitro was investigated by administering peroxynitrite donor (3-morpholino-sydnonimine, SIN-1) and peroxynitrite (FeTMPyP). The roles of nitrative stress on cell viability, necrosis and apoptosis were evaluated with 3-(4,5-dimethylthiazol)-2,5-diphenyl tetrazolium (MTT) assay, lactate dehydrogenase (LDH) release assay and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay, respectively. Also, the phospho-eNOS expression and tube formation in Matrigel of cultured EPCs was detected. Our data showed that the survival of EPCs was much lower in SIN-1 group than in vehicle group, both the apoptosis and necrosis of EPCs were much more severe, and the p-eNOS expression and tube formation in Matrigel were obviously declined. Subsequent pretreatment with FeTMPyP reversed these changes. Further, pretreatment with FeTMPyP reversed homocysteine-induced EPC injury. In conclusion, this study indicates that nitrative stress plays a role in vascular endothelial injury in hyperhomocysteinemia, as well as induces endothelial progenitor cell injury directly. [ABSTRACT FROM AUTHOR]

Background: We have previously reported that high glucose impairs coronary vasodilation by reducing voltage-gated K+ (Kv) channel activity. However, the underlying mechanisms remain unknown. Advanced glycation end products (AGEs) are potent factors that contribute to the development of diabetic vasculopathy. The aim of this study was to investigate the role of AGEs in high glucose-induced impairment of Kv channels-mediated coronary vasodilation. Methods: Patch-clamp recording and molecular biological techniques were used to assess the function and expression of Kv channels. Vasodilation of isolated rat small coronary arteries was measured using a pressurized myograph. Treatment of isolated coronary vascular smooth muscle cells (VSMCs) and streptozotocin-induced diabetic rats with aminoguanidine, the chemical inhibitor of AGEs formation, was performed to determine the contribution of AGEs. Results: Incubation of VSMCs with high glucose reduced Kv current density by 60.4 ± 4.8%, and decreased expression of Kv1.2 and Kv1.5 both at the gene and protein level, whereas inhibiting AGEs formation or blocking AGEs interacting with their receptors prevented high glucose-induced impairment of Kv channels. In addition, diabetic rats manifested reduced Kv channels-mediated coronary dilation (9.3 ± 1.4% vs. 36.9 ± 1.4%, P < 0.05), which was partly corrected by the treatment with aminoguanidine (24.4 ± 2.2% vs. 9.3 ± 1.4%, P < 0.05). Conclusions: Excessive formation of AGEs impairs Kv channels in VSMCs, then leading to attenuation of Kv channels-mediated coronary vasodilation. [ABSTRACT FROM AUTHOR]

Background: Previous studies showed that autoantibodies (M2-AA) against the second extracellular loop of M2 muscarinic receptor (M2AChR-el2) from dilated cardiomyopathy (DCM) serum could induce DCM-like morphological changes in mice hearts. However, the effects of M2-AA on the cardiac function during the process of DCM and the potential mechanisms are not fully known. The present study was designed to dynamically observe the cardiac function, mitochondrial changes, and M2 receptor binding characteristics in rats long-term stimulated with M2-AA in vivo. Methods: M2-AA-positive model was established by actively immunizing healthy male Wistar rats with synthetic M2AChR-el2 peptide for 18 months. Meanwhile, vehicle group rats were administrated with physiological saline. The change of mitochondrial membrane potential (ΔΨm) was detected by radionuclide imaging. The ultrastructure of mitochondria was observed under electron microscopy. The M2 receptor binding characteristics were determined by radioactive ligand binding assay. Results: After immunization for 12 months, compared with vehicle group, M2AChR-el2-immunized rats showed decreased myocardial contractility and cardiac diastolic function evidenced by declined maximal rate of rise of ventricular pressure and increased left ventricular end-diastolic pressure, respectively. Additionally, mitochondrial swelling and vacuolation were observed. At 18 months, M2AChR-el2-immunized rats manifested significant decreased cardiac systolic and diastolic function and pathological changes such as enlargement of right ventricular cavity and wall thinning; and the mitochondrial damage was aggravated. Furthermore, the M2 receptor maximum binding capacity (Bmax) of the M2AChR-el2-immunized rats significantly decreased, while the M2 receptor dissociation constant (Kd) was increased. Conclusions: Our study suggested that long-term stimulation with M2-AA leaded to the ventricular dilatation and gradual deterioration of cardiac dysfunction. Mitochondrial damage and the down-regulation of M2 receptor density and affinity may be involved in the process. [ABSTRACT FROM AUTHOR]

Declined vasorelaxation function in aging resistance arteries is responsible for aging-related multiple organ dysfunctions. The aim of the present study is to explore the role of peroxynitrite (ONOO-) in aging resistance arterial vasorelaxation dysfunction and the possible mechanism. In the present study, young (3–4 months olds) and aging (20 months olds) male SD rats were randomized to receive vehicle (Saline) or FeTMPyP (ONOO- scavenger) for 2 weeks. The vasorelaxation of resistance arteries was determined in vitro; NOx level was tested by a colorimetric assay; the expression of nitrotyrosine (NT), soluble Guanylate Cyclase (sGC), vasodilator-stimulated phosphoprotein (VASP), phosphorylated VASP (P-VASP) and cGMP in resistance arteries were detected by immunohistochemical staining. In the present study, endothelium-dependent dilation in aging resistance arteries was lower than in those from young rats (young vs. aging: 68.0%±4.5% vs. 50.4%±2.9%, P<0.01). And the endothelium-independent dilation remained constant. Compared with young rats, aging increased nitrative stress in resistance arteries, evidenced by elevated NOx production in serum (5.3±1.0 nmol/ml vs. 3.3±1.4 nmol/ml, P<0.05) and increased NT expression (P<0.05). ONOO- was responsible for the vasorelaxation dysfunction, evidenced by normalized vasorelaxation after inhibit ONOO- or its sources (P<0.05) and suppressed NT expression after FeTMPyP treatment (P<0.05). The expression of sGC was not significantly different between young and aging resistance arteries, but the cGMP level and P-VASP/VASP ratio (biochemical marker of NO-sGC-cGKs signaling) decreased, which was reversed by FeTMPyP treatment in vivo (P<0.05). The present study suggested that ONOO- mediated the decline of endothelium-dependent vasorelaxation of aging resistance arteries by induction of the NO-sGC-cGKs pathway dysfunction. [ABSTRACT FROM AUTHOR]

Hyperandrogenism is a core factor in the series of reproductive and endocrine metabolic disorders involved in polycystic ovary syndrome (PCOS). Abnormalities in enzymatic activity and the expression of ovarian granular cell layer P450arom and theca cell P450c17α can lead to an atypical environment of local ovarian hormones, including excessive androgen levels. Rat models prepared with letrozole exhibit similar endocrine and histological changes to those that occur in human PCOS. We used such a model to study the role of electro-acupuncture (EA) in regulating ovarian P450arom and P450c17α enzymatic activity and mRNA expression in PCOS rats. Female Sprague Dawley (SD) rats aged 42 days were randomly divided into 3 groups (control, PCOS, and PCOS EA) consisting of 10 rats each. The PCOS and PCOS EA groups were administered a gavage of 1.0 mg/kg−1 of letrozole solution once daily for 21 consecutive days. Beginning in the ninth week, the PCOS EA group was administered low-frequency EA treatment daily for 14 consecutive days. After the treatment, we obtained the following results. The estrous cycles were restored in 8 of the 10 rats in the PCOS EA group, and their ovarian morphologies and ultrastructures normalized. The peripheral blood measurements (with ELISA) showed significantly decreased androgens (i.e., androstenedione and testosterone) with significantly increased estrogens (i.e., estrone, estradiol) and increased P450arom with decreased P450C17α. Immunohistochemistry and Western blotting methods showed enhanced expression of ovarian granular cell layer P450arom as well as decreased expression of theca cell layer P450C17α. Fluorescence quantitative PCR methods showed enhanced expression of ovarian granular cell layer P450arom mRNA as well as decreased expression of theca cell layer P450C17α mRNA. These results may help explain the effects of electro-acupuncture in changing the local ovarian hyperandrogenic environment and improving reproductive and endocrine metabolic disorders in PCOS. [ABSTRACT FROM AUTHOR]

Autophagy is important in cells for removing damaged organelles, such as mitochondria. Insufficient autophagy plays a critical role in tissue injury and organ dysfunction under a variety of pathological conditions. However, the role of autophagy in nonlethal traumatic cardiac damage remains unclear. The aims of the present study were to investigate whether nonlethal mechanical trauma may result in the change of cardiomyocyte autophagy, and if so, to determine whether the changed myocardial autophagy may contribute to delayed cardiac dysfunction. Male adult rats were subjected to nonlethal traumatic injury, and cardiomyocyte autophagy, cardiac mitochondrial function, and cardiac function in isolated perfused hearts were detected. Direct mechanical traumatic injury was not observed in the heart within 24 h after trauma. However, cardiomyocyte autophagy gradually decreased and reached a minimal level 6 h after trauma. Cardiac mitochondrial dysfunction was observed by cardiac radionuclide imaging 6 h after trauma, and cardiac dysfunction was observed 24 h after trauma in the isolated perfused heart. These were reversed when autophagy was induced by administration of the autophagy inducer rapamycin 30 min before trauma. Our present study demonstrated for the first time that nonlethal traumatic injury caused decreased autophagy, and decreased autophagy may contribute to post-traumatic organ dysfunction. Though our study has some limitations, it strongly suggests that cardiac damage induced by nonlethal mechanical trauma can be detected by noninvasive radionuclide imaging, and induction of autophagy may be a novel strategy for reducing posttrauma multiple organ failure. [ABSTRACT FROM AUTHOR]

It has been recognized that changes in mitochondrial structure plays a key role in development of cardiac dysfunction, and autophagy has been shown to exert maintenance of mitochondrial homeostasis effects. Our previous study found that anti-β1-adrenergic receptor autoantibodies (β1-AABs) could lead to cardiac dysfunction along with abnormalities in mitochondrial structure. The present study tested the hypothesis that β1-AABs may induce the decline in mitochondrial membrane potential (ΔΨm) by suppression of cardiac autophagy, which contributed to cardiac dysfunction. Male adult rats were randomized to receive a vehicle or peptide corresponding to the second extracellular loop of the β1 adrenergic receptor (β1-AAB group, 0.4 μg/g every two weeks for 12 weeks) and treated with rapamycin (RAPA, an autophagy agonist) at 5 mg/kg/day for two days before detection. At the 4th week, 8th week and 12th week of active immunization, the rats were sacrificed and cardiac function and the levels of cardiac LC3 and Beclin-1 were detected. ΔΨm in cardiac myocytes was determined by myocardial radionuclide imaging technology and JC-1 staining. In the present study, β1-AABs caused cardiac dysfunction, reduced ΔΨm and decreased cardiac autophagy. Treatment with RAPA markedly attenuated β1-AABs-induced cardiac injury evidenced by recovered ΔΨm. Taken together, these results suggested that β1-AABs exerted significant decreased ΔΨm, which may contribute to cardiac dysfunction, most likely by decreasing cardiac autophagy in vivo. Moreover, myocardial radionuclide imaging technology may be needed to assess the risk in developing cardiac dysfunction for the people who have β1-AABs in their blood. [ABSTRACT FROM AUTHOR]

β3-adrenoceptors (β3-ARs) mediate a negative inotropic effect in human ventricular cardiomyocytes, which is opposite to that of β1- and β2-ARs. It has been previously demonstrated that autoantibodies against the β1/β2-AR exist in the sera of some patients with heart failure (HF) and these autoantibodies display agonist-like effects. Our aim in this study was to observe whether autoantibodies against the β3-AR (β3-AR Abs) exist in the sera of patients with HF and to assess the effects of β3-AR Abs on rat model of pressure overload cardiomyopthy. In the present study, the level of β3-AR Abs in the sera of HF patients was screened by ELISA. β3-AR Abs from HF patients were administrated to male adult rats with abdominal aortic banding (AAB), and the cardiac function was measured by echocardiographic examination and hemodynamic studies. The biological effects of this autoantibody on cardiomyocytes were evaluated using a motion-edge detection system, intracellular calcium transient assay, and patch clamp techniques. Compared to healthy subjects, the frequency of occurrence and titer of β3-AR Abs in the sera of HF patients were greatly increased, and β3-AR Abs could prevent LV dilation and improve the cardiac function of rats with AAB. β3-AR Abs exhibited negative chronotropic and inotropic effects and were accompanied by a decreased intracellular Ca2+ transient and membrane L-type Ca2+ current in cardiomyocytes. Our results demonstrated the existence of β3-AR Abs in the sera of patients with HF and found that this autoantibody could alleviate the cardiac dysfunction induced by pressure-overload in AAB rats. [ABSTRACT FROM AUTHOR]