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+-H+ exchanger with 10 μmol/L ethylisopropylamiloride but was abolished in bicarbonate-free buffer. Recovery from an ammonium chloride prepulse-induced acid load occurred more rapidly when fluid shear stress was abruptly reduced from 2.7 to 0.3 dyne/cm2 after maximal acidification (+0.04±0.02 pH unit at 2 minutes) than when shear stress was maintained at 2.7 dyne/cm2 continuously (0.00±0.00 pH unit at 2 minutes, P+, indicating that the acute reduction in fluid shear stress activates the extracellular Na+-dependent Cl--HCO3- exchanger and the Na+-H+ exchanger and increases cytosolic pH in vascular endothelial cells.
|Number of pages||7|
|Publication status||Published - Apr 20 1998|
- Carboxy-seminaphthorhodafluor- 1
- Cytosolic pH
- Shear stress
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine