Role of Rho kinase in the dysfunction of myocardium contraction in hemorrhagic shock rats

AIM: To explore the role of Rho kinase in myocardium contraction in hemorrhagic shock rats. METHODS: The rat cardiac papillary muscle and rat heart at different time points during hemorrhagic shock were isolated. The contraction of papillary muscle in response to isoprenaline and the hemodynamic parameters of the isolated hearts in vitro including left intraventricular systolic pressure (LVSP), the maximal change rate of left intraventricular pressure (±dp/dtmax) were measured. RESULTS: The activity of Rho kinase, the contractile response of cardiac papillary muscle to isoprenaline and the hemodynamic parameters of the hearts were decreased gradually at the 1 h, 2 h and 4 h after shock. Compared to the normal controls, the activity of Rho kinase, the contractile response of cardiac papillary muscle and the hemodynamic parameters of the hearts were decreased significantly. The change of Rho kinase was positively correlated with the contractile response and the hemodynamic parameters of the heart. Stimulation with U-46619 at concentration of 10-8 mmol/L increased the activity of Rho kinase and improved the contractile response of cardiac papillary muscle to isoprenaline and the hemodynamic parameters of the isolated heart. The effects of U-46619 on the above parameters were abolished by Rho kinase specific inhibitor Y-27632 at concentration of 10-5 mol/L. CONCLUSION: Rho kinase plays an important role in the regulation of cardiac contractility during hemorrhagic shock.