Pharmacological modulation of 86Rb efflux from aortic endothelial cells.

The ATP-induced efflux of 86Rb from prelabelled bovine aortic endothelial cells was inhibited by quinine (50 microM) but not by a tetraethylammonium (5 mM) or apamin (50 nM). Neither sulfonylureas nor pinacidil had a significant effect on the rate of 86Rb efflux from the endothelial cells. These data are consistent with the presence of intermediate conductance Ca2(+)-activated K+ channels in endothelial cells. ATP-dependent K+ channels, sensitive to sulfonylureas and pinacidil, could not be detected.