Apamin-sensitive Ca2+-dependent K+ current and hyperpolarization in human endothelial cells.
Vascular endothelial cells have several types of Ca2+-dependent K+ current (I(K-Ca)). Here, we describe apamin-sensitive I(K-Ca) which is activated by treatment with histamine (His) in human umbilical vein endothelial cells (HUVECs). In 65 % of HUVECs examined, 100 nM apamin potently inhibited I(K-Ca) and hyperpolarization induced by His (19 and 7 % of control, respectively). In contrast, application of 5 mM tetraethylammonium, a non-selective K channel blocker, or 100 nM iberiotoxin, a selective K channel blocker for a large conductance Ca2+-dependent K+ channel, had small (78 % of control) or no effects (102 % of control) on I(K-Ca), respectively. These findings suggest that apamin-sensitive Ca2+-dependent K+ channels are expressed in HUVECs and activated by receptor stimulation.
Muraki
K
K
Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Nagoya City University, Mizuhoku, Nagoya, Japan.
Imaizumi
Y
Y
Ohya
S
S
Sato
K
K
Takii
T
T
Onozaki
K
K
Watanabe
M
M
D001030:Apamin / Q000494:pharmacology*; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000502:physiology*; D002478:Cells, Cultured; D004730:Endothelium, Vascular; D006632:Histamine / Q000494:pharmacology; D006801:Humans; D015640:Ion Channel Gating; D007476:Ionophores / Q000494:pharmacology; D008564:Membrane Potentials; D010455:Peptides / Q000494:pharmacology; D015221:Potassium Channels / Q000502:physiology*; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology
D007476:Ionophores; D010455:Peptides; D015221:Potassium Channels; D013757:Tetraethylammonium Compounds; D001030:Apamin; D000001:Calcimycin; D019789:Tetraethylammonium; C064719:iberiotoxin; D006632:Histamine; D002118:Calcium