Cx40和Cx43调节大鼠肠系膜上动脉收缩反应性与钙敏感性的机制

Regulatory mechanism of Cx40 and Cx43 on endothelium-dependent vascular contractile reactivity in rat superior mesenteric artery

目的:研究连接蛋白Cx40/Cx43对大鼠肠系膜上动脉内膜依赖的血管收缩反应性与钙敏感性的调节作用机制。方法:以SD大鼠肠系膜上动脉(SMA)为研究对象,用Cx40或Cx43反义寡脱氧核苷酸(Cx40/Cx43AODN)阻断SMA Cx40或Cx43表达,观察缺氧处理后SMA的收缩反应性、钙敏感性、肌球蛋白轻链磷酸酶/激酶(MLCP/MLCK)的活性、20kD的肌球蛋白轻链(MLC20)磷酸化程度的变化。结果:Cx40AODN可以降低正常组、1h和3h缺氧组SMA MLCP活性,增加MLC20磷酸化水平,改善血管的钙敏感性和内膜依赖的收缩反应性;Cx43AODN可以增加各组血管的MLCP活性,减少MLC20磷酸化水平,降低血管的钙敏感性和内膜依赖的收缩反应性。Cx40和Cx43AODN对SMA MLCK活性无明显作用。结论:Cx40和Cx43主要通过调节血管平滑肌细胞的MLCP活性和MLC20磷酸化水平调节血管的钙敏感性,从而调节休克后内膜依赖的血管收缩反应性。

AIM： To investigate the regulatory mechanism of Cx40 and Cx43 on endothelium -dependent vascular contractile reactivity and calcium sensitivity following hemorrhagic shock in rats. METHODS： The rat superior mesenteric arteries （SMAs） were isolated and vascular rings were prepared. Transfection of Cx40 and Cx43 antisense oligodeoxyribonucleotide （Cx40 and Cx43AODN ） was conducted to block the expressions of Cx40 and Cx43 in SMAs. The changes of contractile response, calcium sensitivity, the activity of myosin light chain phosphatase （MLCP） and myosin light chain kinase （MLCK）, 20kD myosin light chain （MLC20） phosphorylation in hypoxia treated SMA were observed. RESULTS： Cx40AODN decreased the activity of MLCP, increased the MLC20 phosphorylation, by which Cx40AODN improved the calcium sensitivity and the contractile response of SMA. Cx43AODN increased the activity of MLCP, reduced the MLC20 phosphorylation, by which Cx43AODN depressed the calcium sensitivity and the contractile response of SMA. No effect of Cx40 and Cx43AODN on the MLCK＇s activity of SMA was observed. CONCLUSION： The mechanism that Cx40 and Cx43 regulates endothelium -dependent vaso -contractile responses following hemorrhagic shock may be mainly through regulating the activity of MLCP and MLC20 phosphorylation in vascular smooth muscle cells.