%0 Journal Article
%T The actin cytoskeleton and small G protein RhoA are not involved in flow-dependent activation of ENaC
%A Alexey V Karpushev
%A Daria V Ilatovskaya
%A Alexander Staruschenko
%J BMC Research Notes
%D 2010
%I BioMed Central
%R 10.1186/1756-0500-3-210
%X Pretreatment with Cytochalasin D and Latrunculin B for 20 min and 1-2 hrs to disassemble F-actin had no effect on flow-mediated increase of amiloride-sensitive current. Overexpression of ENaC with constitutively active (G14V) or dominant negative (T19N) RhoA similarly had no effect on flow-dependent activation of ENaC activity. In addition, we did not observe changes when we inhibited Rho-kinase with Y27632.Our results suggest that the flow-dependent activation of ENaC is not influenced by small GTPase RhoA and modifications in the actin cytoskeleton.The long term control of blood pressure involves Na+ homeostasis through the precise regulation of the Epithelial Na+ Channel (ENaC) in the aldosterone-sensitive distal nephron [1,2]. The rate of Na+ absorption varies widely in response to conditions of Na+ deprivation and Na+ excess. The physiological relevance of the mechanosensitivity of ENaC becomes clearly apparent in the mammalian cortical collecting ducts (CCDs), a nephron segment subject to continuous variations in rates of tubular flow. Flow rates within the distal nephron, including CCDs, increase in response to expansion of the extracellular fluid volume or administration of diuretics and fall in response to volume depletion [3]. Palmer and Frindt studied whether mechanical perturbations could influence ENaC kinetics or gating mode in freshly isolated rat CCDs. In most cases negative pressure applied to the patch clamp pipette had no effect on channel behaviour. However they also observed a rapid and reversible increase in channel open probability (Po) in 6 out of 22 patches [4]. In one experiment, there was a reversible decrease. They proposed that the variability in the response could reflect differences in the mechanical deformations of the apical membrane within the tip of the pipette [4]. Later Awayda and Subramanyam proposed that rENaC is not directly mechanosensitive when overexpressed in oocytes [5]. However, recent data are mostly supportive of ENaC'
%U http://www.biomedcentral.com/1756-0500/3/210