Cytosolic alkalinization of vascular endothelial cells produced by an abrupt reduction in fluid shear stress

Abstract

Reductions in fluid shear stress produce endothelium-dependent vasoconstriction and promote neointimal hyperplasia, but the intracellular signaling mechanisms involved in these processes are poorly understood. To examine whether decreases in fluid shear stress affect endothelial cytosolic pH, carboxy-seminaphthorhodafluor-1-loaded rat aortic endothelial cells were cultured in glass microcapillary tubes and examined during abrupt reductions in laminar flow. After a 30-minute exposure to a shear stress of 2.7 dyne/cm2 in bicarbonate buffer, the acute reduction of fluid shear stress from 2.7 to 0.3 dyne/cm2 transiently increased cytosolic pH from 7.20±0.02 to 7.47±0.07 (mean±SEM, P