Differential effects of superoxide and hydrogen peroxide on myogenic signaling, membrane potential and contractions of mouse renal afferent arterioles.

Differential effects of superoxide and hydrogen peroxide on myogenic signaling, membrane potential and contractions of mouse renal afferent arterioles. Am J Physiol Renal Physiol. 2016 Apr 6;:ajprenal.00575.2015 Authors: Li L, Lai EY, Wellstein A, Welch WJ, Wilcox CS Abstract Myogenic contraction is the principal component of renal autoregulation that protects the kidney from hypertensive barotrauma. Contractions are initiated by a rise in perfusion pressure that signals a reduction in membrane potential (Em) of vascular smooth muscle cells to activate voltage operated calcium channels (VOCCs). Since reactive oxygen species (ROS) have variable effects on myogenic tone, we investigated the hypothesis that superoxide (O2 (.-)) and hydrogen peroxide (H2O2) differentially impact myogenic contractions. The myogenic contractions of mouse isolated and perfused single afferent arterioles were assessed from changes in luminal diameter with increasing perfusion pressure (40 to 80 mmHg). O2 (.-), H2O2and Em were assessed by fluorescence microscopy during incubation with paraquat to increase O2 (.-)or with H2O2 Paraquat enhanced O2 (.-)generation and myogenic contractions ( -42±4 % versus -19±4%; p<0.005) that were blocked by superoxide dismutase but not by catalase and signaled via protein kinase C. In contrast, H2O2inhibited the effects of paraquat and reduced myogenic contractions (-10±1% versus -19±2%; p<0.005) and signaled via pro...
Source: Am J Physiol Renal P... - Category: Urology & Nephrology Authors: Tags: Am J Physiol Renal Physiol Source Type: research