Role of Rho-kinase in vascular hyporeactivity following hemorrhagic shock in rats

Objective To observe the role of Rho-kinase in vascular hyporeactivity following hemorrhagic shock(HS) in rats.Methods The superior mesenteric artery(SMA) from hemorrhagic shock rats was adopted to assay the vascular reactivity,and calcium sensitivity via observing the contraction initiated by norepinephrine(NE) and Ca~(2+) under depolarizing conditions(120mmol/L K~(+)) with isolated organ perfusion system.At the same time,Rho-kinase activity in SMA was measured.The relationship among the vascular reactivity,calcium sensitivity and Rho-kinase activity was analyzed;meanwhile,the effect of the Ang-Ⅱ and Y-27632 of Rho-kinase activity regulating agents on vascular reactivity was also observed.Results As compared with the control group,the cumulative dose-response curves of SMA to NE and Ca~(2+) at early period of shock shifted to the left,the maximal contractions(Emax) of NE and Ca~(2+) was increased significantly(P0.05 or P0.01).But the cumulative dose-response curves of SMA to NE and Ca~(2+) on 1,2h after shock shifted to the right,the maximal contractions(Emax) of NE and Ca~(2+) were significantly decreased(P0.05 or P0.01).Rho-kinase activity was significantly increased in the period of early shock(P0.05),but significantly decreased on 1,2h after shock(P0.05 or P0.01).Ang-Ⅱ increased the contractile response of SMA to NE and Ca~(2+) on 2h after shock,which made the cumulative dose-response curve of NE and Ca~(2+) shift to the left(P0.05 or P0.01);Y-27632 decreased the contractile response of SMA to NE and Ca~(2+),which made the cumulative dose-response curves of NE and Ca~(2+) shift to the right(P(0.05) or P0.01).Conclusion Rho-kinase can regulate vascular reactivity via!calcium sensitivity regulation.The changes of vascular reactivity following hemorrhagic shock was closely associated with the changes of Rho-kinase activity in SMA.Rho-kinase plays an important role in vascular hyporeactivity following hemorrhagic shock.