Author:
Chang Shaohua,Hypolite Joseph A.,DiSanto Michael E.,Changolkar Arun,Wein Alan J.,Chacko Samuel
Abstract
Urinary bladder dysfunction caused by the alteration of detrusor smooth muscle (DSM) is one of the complications of diabetes. It is well established that smooth muscle contractility is regulated by an elevation of cytosolic Ca2+ via myosin light chain (MLC) phosphorylation. However, recent studies have shown the modulation of MLC phosphorylation without a rise in Ca2+ in smooth muscle and that two key molecules (Rho-kinase and CPI-17) are involved in the regulation of calcium sensitization. This study investigates the effect of diabetes on DSM calcium sensitization. Diabetes was induced by alloxan in New Zealand White rabbits, and age-matched rabbits given 5% sucrose in the drinking water served as control for diuresis. Two-dimensional gel electrophoresis showed that basal MLC phosphorylation level was significantly higher in diabetic animals than normal or diuretic controls, and Rho-kinase-specific inhibitor, Y-27632, decreased MLC phosphorylation level. Adding Y-27632 to bethanechol-precontracted DSM strips can induce muscle relaxation, but it occurred much more slowly in diabetic samples compared with controls. RT-PCR, Western blot analysis, and immunohistochemistry revealed the overexpression of Rho-kinase β and CPI-17 at both mRNA and protein levels in response to diabetes. In conclusion, our results demonstrate that Rho-kinase contributes to DSM MLC phosphorylation and there is a higher basal MLC phosphorylation level in diabetic DSM. Our results also suggest that this high basal MLC phosphorylation may be due to the upregulation of Rho-kinase and CPI-17. Thus Rho-kinase- and CPI-17-mediated Ca2+ sensitization might play a role in diabetes-induced alteration of the detrusor contractility and bladder dysfunction.
Publisher
American Physiological Society
Cited by
54 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献