S-Nitrosylation of Prostacyclin Synthase Instigates Nitrate Cross-Tolerance In Vivo.

Development of nitrate tolerance is a major drawback to nitrate therapy. Prostacyclin (PGI2) is a powerful vasodilator produced from prostaglandin (PGH2) by prostacyclin synthase (PGIS) in endothelial cells. This study aimed to determine the role of PGIS S-nitrosylation in nitrate tolerance induced by nitroglycerin (GTN). In endothelial cells, GTN increased PGIS S-nitrosylation and disturbed PGH2 metabolism, which were normalized by mutants of PGIS cysteine 231/441 to alanine (C231/441A). Clearance of nitric oxide by carboxy-PTIO or inhibition of S-nitrosylation by N-acetyl-cysteine decreased GTN-induced PGIS S-nitrosylation. Enforced expression of mutated PGIS with C231/441A markedly abolished GTN-induced PGIS S-nitrosylation and nitrate cross-tolerance in Apoe-/- mice. Inhibition of cyclooxygenase 1 by aspirin, supplementation of PGI2 by beraprost, and inhibition of PGIS S-nitrosylation by N-acetyl-cysteine improved GTN-induced nitrate cross-tolerance in rats. In patients, increased PGIS S-nitrosylation was associated with nitrate tolerance. In conclusion, GTN induces nitrate cross-tolerance through PGIS S-nitrosylation at cysteine 231/441.

Angiotensin II type 1 receptor blockers prevent aortic arterial stiffness in elderly patients with hypertension.

Backgrounds and aims: Increased arterial stiffness may increase cardiovascular morbidity and mortality. Angiotensin II type 1 receptor blockers (ARBs) are potentially useful in controlling the central blood pressure and arterial stiffness in mild to moderate essential hypertension, while the effects of ARBs in aged patients with essential hypertension are not entirely investigated. Methods: The carotid-femoral arterial pulse wave velocity (PWV) was measured in aged patients with essential hypertension. Results: In a cross-sectional study, PWV value was significantly higher in these old patients with essential hypertension, compared to patients without essential hypertension. In correlation analysis, PWV was associated positively with age, hypertension duration, and carotid atherosclerosis. However, there was no relationship between PWV and gender in aged patients with essential hypertension. In a perspective study, 6-12 months administration of ARBs (losartan, 50 mg/day; telmisartan, 40 mg/day; valsartan 80 mg/day; irbesartan, 150 mg/day) remarkably reduced PWV in aged patients with essential hypertension. Regression analyses of multiple factors indicated that the effects of ARBs on arterial stiffness were not associated with the reduction of blood pressure. Conclusion: ARB treatment is a negative risk factor of arterial stiffness in aged patients with essential hypertension.

Vitamin B6 prevents isocarbophos-induced vascular dementia in rats through N-methyl-D-aspartate receptor signaling.

BACKGROUND: We have previously reported that the long-term exposure of organophosphorus induces vascular dementia (VD) in rats. As a coenzyme, vitamin B6 is mainly involved in the regulation of metabolisms. Whether vitamin B6 improves VD remains unknown. METHODS: The model of VD was induced by feeding rats with isocarbophos (0.5 mg/kg per two day, 12 weeks). The blood flow of the posterior cerebral artery (PCA) in rat was assessed by transcranial Doppler (TCD). The learning and memory were evaluated by the Morris Water Maze (MWM) test. RESULTS: Administration of vitamin B6 increased the blood flow in the right and left posterior cerebral arteries and improved the functions of learning and memory in isocarbophos-treated rats. Vitamin B6 increased the protein levels of N-methyl-D-aspartate receptor (NMDAR) 2B, postsynaptic densities (PSDs) protein 95, and calmodulin-dependent protein kinase II (CaMK-II) in the hippocampus, which were decreased by isocarbophos in rats. Morphological analysis by light microscope and electronic microscope indicated disruptions of the hippocampus caused by isocarbophos were normalized by vitamin B6. Importantly, the antagonist of NMDAR signaling by eliprodil abolished these beneficial effects produced by vitamin B6 on PCA blood flow, learning, memory, and hippocampus structure in rats, as well as the protein expression of NMDAR 2B, PSDs protein 95, and CaMK-II in the hippocampus. CONCLUSION: Vitamin B6 activates NMDAR signaling to prevent isocarbophos-induced VD in rats.

Traditional Chinese medicine Ka-Sai-Ping suppresses the growths of gastric cancers via induction of autophagy.

Traditional Chinese medication is increasingly used to treat a wide range of human chronic diseases like cardiovascular diseases and cancers. This study was designed to explore whether ka-sai-ping (KSP), a novel traditional Chinese medicine developed by us, prevents gastric cancer growths and to investigate the underlying mechanism. The xenograft model of mouse gastric cancer was established by injecting MFCs into nude mouse subcutaneously. Cell autophagy was assessed by MDC staining. Lysosome and mitochondria were detected by Lyso-Tracker Red and Mito-Traker Green staining. Incubation of cultured mouse gastric cancer cell line MFCs with KSP for 48 hours, concentration-dependently reduced cell survivals and activated autophagy, which were accompanied with damaged lysosomes and mitochondria. In vivo studies indicated that KSP therapy (20 ml/kg/day) for two weeks suppressed the growth of gastric cancer, increased the protein levels of LC3-II, beclin-1, cathepsin L, bcl-2, p53, and capase-3 in tumor tissues from the xenograft model of mouse gastric cancer. Importantly, all these effects induced by KSP were abolished by co-administration of autophagy inhibitor 3-MA. In conclusion, KSP activates cell autophagy to suppress gastric cancer growths. Clinically, KSP is potentially considered as a medicine to treat patients with gastric cancer.

Traditional Chinese medicine xin-mai-jia recouples endothelial nitric oxide synthase to prevent atherosclerosis in vivo.

Endothelial dysfunction, which is caused by endothelial nitric oxide synthase (eNOS) uncoupling, is an initial step in atherosclerosis. This study was designed to explore whether Chinese medicine xin-mai-jia (XMJ) recouples eNOS to exert anti-atherosclerotic effects. Pretreatment of XMJ (25, 50, 100 µg/ml) for 30 minutes concentration-dependently activated eNOS, improved cell viabilities, increased NO generations, and reduced ROS productions in human umbilical vein endothelial cells incubated with H2O2 for 2 hours, accompanied with restoration of BH4. Importantly, these protective effects produced by XMJ were abolished by eNOS inhibitor L-NAME or specific eNOS siRNA in H2O2-treated cells. In ex vivo experiments, exposure of isolated aortic rings from rats to H2O2 for 6 hours dramatically impaired acetylcholine-induced vasorelaxation, reduced NO levels and increased ROS productions, which were ablated by XMJ in concentration-dependent manner. In vivo analysis indicated that administration of XMJ (0.6, 2.0, 6.0 g/kg/d) for 12 weeks remarkably recoupled eNOS and reduced the size of carotid atherosclerotic plaque in rats feeding with high fat diet plus balloon injury. In conclusion, XMJ recouples eNOS to prevent the growth of atherosclerosis in rats. Clinically, XMJ is potentially considered as a medicine to treat patients with atherosclerosis.

Chronic administration of isocarbophos induces vascular cognitive impairment in rats.

Vascular dementia, being the most severe form of vascular cognitive impairment (VCI), is caused by cerebrovascular disease. Whether organophosphorus causes VCI remains unknown. Isocarbophos (0.5 mg/kg per 2 days) was intragastrically administrated to rats for 16 weeks. The structure and function of cerebral arteries were assayed. The learning and memory were evaluated by serial tests of step-down, step-through and morris water maze. Long-term administration of isocarbophos reduced the hippocampal acetylcholinesterase (AChE) activity and acetylcholine (ACh) content but did not alter the plasma AChE activity, and significantly damaged the functions of learning and memory. Moreover, isocarbophos remarkably induced endothelial dysfunction in the middle cerebral artery and the expressions of ICAM-1 and VCAM-1 in the posterior cerebral artery. Morphological analysis by light microscopy and electron microscopy indicated disruptions of the hippocampus and vascular wall in the cerebral arteries from isocarbophos-treated rats. Treatment of isocarbophos injured primary neuronal and astroglial cells isolated from rats. Correlation analysis demonstrated that there was a high correlation between vascular function of cerebral artery and hippocampal AChE activity or ACh content in rats. In conclusion, chronic administration of isocarbophos induces impairments of memory and learning, which is possibly related to cerebral vascular dysfunction.

[Role of ventricular M3 receptor in arrhythmia resulted from cerebral-cardiac syndrome].

To detect the function and expression of ventricular M3 receptor (M3R) in cerebral-cardiac syndrome (CCS) model rats and to explore the relationship between the expression of M3R and the arrhythmia resulted from CCS, CCS model rats were induced by occluding right middle cerebral artery. ECG was monitored. Intracellular calcium ([Ca2+]i) changes after agitating M3R were recorded by laser scanning confocal microscope. Changes of M3R expression in the ventricular tissue were detected by Western blotting. QRS and QT intervals in CCS group were remarkably longer than that in sham group. According to the results of Western blotting, the level of M3R expression was remarkably lower in CCS group compared with that in the normal group. KCl induced [Ca2+]i increasing in CCS group could be depressed by choline and the effect of choline could be blocked by 4-DAMP. The lower expression of M3R in CCS group may be one of important reasons of arrhythmia resulted from CCS. M3R that depressed the [Ca2+]i increasing agitated by choline may become a new target to cure arrhythmia resulted from CCS.