| Hydrogen sulfide is a colorless and poisonous gas with an offensive stench which smells like rotten eggs. However, it has been found recently that H2S can be endogenously synthesized in mammalian body. H2S is regarded as the third kind of endogenous gas signaling molecular after Nitric oxide (NO) and carbon monoxide (CO) and is involved in regulating various in vitro physiological and pathological processes. Endothelium-derived hyperpolarizing factor (EDHF) is one kind of endothelium-derived relaxing factor and is ranks as the third kind of autacoids which can control blood vessels stability and play role in vasodilation after NO and prostacyclin (PGI2). The recent research in our lab has found that the EDHF reaction on rat cerebral basilar artery might be induced by H2S. Middle cerebral artery (MCA) is one of the critical supplying vessels in brain. In the current thesis, EDHF-mediated hyperpolarization of rat MCA vascular smooth muscle cells (VSMC) resting potential was studied and H2S was involved with EDHF reaction in this effect .PurposeTo probe the relation of H2S to EDHF mediated hyperpolarization of VSMC resting potential in rat MCA.Method1. The resting potential of VSMC in rat MCA was recorded by using microelectrode method. 2. Rat middle cerebral artery occlusion was used to make focal cerebral ischemia/reperfusion model. H2S level in cerebrum were detected, the abnormal nervous sympom was observed to make clear the difference between control group and the focal cerebral ischemia/reperfusion model group.3. Rat MCA endothelial cells were obtained by using immune magnetic cell separation system method , the mRNA of cystathionine-γ-lyase (CSE) was detected by RT-PCR .Results1. 10-7 10-4.5 mol/L ACh produced concentration dependant hyperpolarization of VSMC in rat MCA VSMC in the presence and absence of NOS inhibitor L-NAME (3×10-5mol /L) and PGI2 syntheses inhibitor Indo (10-5mol/L). TEA (1×10-3 mol/L) , or PPG (10-4 mol/L) , an inhibitor of H2S synthese- CSE can block ACh-induced hyperplarization in the presence of L-NAME and Indo.2. In VSMC of rat MCA , NaHS (10-5-10-2.5 mol/L), a donor of H2S, has the concentration dependent hyperlarization that was inhibited by 1×10-3 mol/L TEA .3. Pre-incubation blood vessels with 10-5-10-2.5mol/L L-Cys, the substrate of H2S synthesis, a concentration dependent hyperlarzation effect was induced. However, the removal of VSMC in rat MCA or 1×10-4 mol/LPPG almost completely blocked hyperlarzation of VSMC in endothelium-intaked rat MCA.4. The expression of CSE mRNA was found in the endothelial cell of rat MCA.5.The contents of H2S were increased in the cerebrum of rat subjected to cerebral ischemia/reperfusion. EDHF-mediated hyperlarzation of VSMC in rat MCA was enhanced by cerebral ischemia/reperfusion.ConclusionH2S was involved with EDHF-mediated hyperlarzation of VSMC in rat MCA, and the hyperlarzation was enhanced by cerebral ischemia/reperfusion.
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