APAMIN-SENSITIVE CA2-DEPENDENT K+ CURRENT AND HYPERPOLARIZATION IN HUMAN ENDOTHELIAL-CELLS()

Vascular endothelial cells have several types of Ca2+- dependent K+ cu rrent (IK-Ca). Here, we describe apamin-sensitive IK-Ca which is activ ated by treatment with histamine (His) in human umbilical vein endothe lial cells (HUVECs), In 65 % of HUVECs examined, 100 nM apamin potentl y inhibited IK-Ca and hyperpolarization induced by His (19 and 7 % of control, respectively). In contrast, application of 5 mM tetraethylamm onium, a non-selective K channel blocker, or 100 nM iberiotoxin, a sel ective K channel blocker for a large conductance Ca2+-dependent K+ cha nnel, had small (78 % of control) or no effects (102 % of control) on IK-Ca, respectively, These findings suggest that apamin-sensitive Ca2-dependent K+ channels are expressed in HUVECs and activated by recept or stimulation, (C) 1997 Academic Press.