Intracellular pH in the resistance vasculature: Regulation and functional implications

Abstract

Net acid extrusion from vascular smooth muscle (VSMCs) and endothelial cells (ECs) in the wall of resistance arteries is mediated by the Na +,HCO3- cotransporter NBCn1 (SLC4A7) and the Na+/H+ exchanger NHE1 (SLC9A1) and is essential for intracellular pH (pHi) control. Experimental evidence suggests that the pHi of VSMCs and ECs modulates both vasocontractile and vasodilatory functions in resistance arteries with implications for blood pressure regulation. The connection between disturbed pHi and altered cardiovascular function has been substantiated by a genome-wide association study showing a link between NBCn1 and human hypertension. On this basis, we here review the current evidence regarding (a) molecular mechanisms involved in pHi control in VSMCs and ECs of resistance arteries at rest and during contractions, (b) implications of disturbed pHi for resistance artery function, and (c) involvement of disturbed pHi in the pathogenesis of vascular disease. The current evidence clearly implies that pHi of VSMCs and ECs modulates vascular function and suggests that disturbed pHi either consequent to disturbed regulation or due to metabolic challenges needs to be taken into consideration as a mechanistic component of artery dysfunction and disturbed blood pressure regulation. Copyright © 2012 S. Karger AG, Basel.