Flow-mediated NO release from endothelial cells is independent of K+ channel activation or intracellular Ca2+.
The role of K+ channels and intracellular [Ca2+] in flow-induced nitric oxide (NO) production was investigated in bovine aortic endothelial cells in culture. NO release (measured as nitrite production) and K+ channel activity (measured as 86Rb+ efflux) were measured in cells grown on collagen-coated microcarrier beads and perfused in a column. An eightfold increase in flow produced a rapid (within 1 min), sustained, and reversible sixfold increase in NO release. Efflux of 86Rb+ also increased but rapidly returned to baseline and then transiently decreased when flow was decreased. This was probably due to boundary layer washout rather than to K+ channel activation, because an identical pattern was seen for release of [3H]ouabain. Neither tetraethylammonium nor increasing medium [K+] to block K+ currents prevented flow-induced NO release. Removal of medium Ca2+ or chelation of intracellular Ca2+ also did not block flow-mediated NO release. The results demonstrate that flow rapidly increases NO release from endothelial cells but that this increase in NO release is not dependent on activation of K+ channels or changes in intracellular [Ca2+].
D000818:Animals; D001775:Blood Circulation / Q000502:physiology*; D002118:Calcium / Q000378:metabolism* / Q000502:physiology; D002417:Cattle; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D007425:Intracellular Membranes / Q000378:metabolism*; D008863:Microspheres; D009566:Nitrates / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism; D010042:Ouabain / Q000494:pharmacology; D015221:Potassium Channels / Q000378:metabolism*; D012413:Rubidium / Q000378:metabolism; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology
D009566:Nitrates; D009573:Nitrites; D015221:Potassium Channels; D013757:Tetraethylammonium Compounds; D009569:Nitric Oxide; D010042:Ouabain; D019789:Tetraethylammonium; D012413:Rubidium; D002118:Calcium