Role of endothelial Ni(2+)-sensitive Ca(2+) entry pathway in regulation of EDHF in porcine coronary artery.
Elevation of intracellular Ca(2+) concentration ([Ca(2+)](i)) in endothelial cells is proposed to be required for generation of vascular actions of endothelium-derived hyperpolarizing factor (EDHF). This study was designed to determine the endothelial Ca(2+) source that is important in development of EDHF-mediated vascular actions. In porcine coronary artery precontracted with U-46619, bradykinin (BK) and cyclopiazonic acid (CPA) caused endothelium-dependent relaxations in the presence of N(G)-nitro-L-arginine (L-NNA). The L-NNA-resistant relaxant responses were inhibited by high K(+), indicating an involvement of EDHF. In the presence of Ni(2+), which inhibits Ca(2+) influx through nonselective cation channels, the BK-induced EDHF relaxant response was greatly diminished and the CPA-induced response was abolished. BK and CPA elicited membrane hyperpolarization of smooth muscle cells of porcine coronary artery. Ni(2+) suppressed the hyperpolarizing responses in a manner analogous to removal of extracellular Ca(2+). EDHF-mediated relaxations and hyperpolarizations evoked by BK and CPA in porcine coronary artery showed a temporal correlation with the increases in [Ca(2+)](i) in porcine aortic endothelial cells. The extracellular Ca(2+)-dependent rises in [Ca(2+)](i) in endothelial cells stimulated with BK and CPA were completely blocked by Ni(2+). These results suggest that Ca(2+) influx into endothelial cells through nonselective cation channels plays a crucial role in the regulation of EDHF.
Tomioka
H
H
Deartments of Pharmacology and Cardiovascular Medicine, Hokkaido University School of Medicine, Sapporo 060-8638, Japan.
Hattori
Y
Y
Fukao
M
M
Watanabe
H
H
Akaishi
Y
Y
Sato
A
A
Kim
T Q
TQ
Sakuma
I
I
Kitabatake
A
A
Kanno
M
M
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D000818:Animals; D001685:Biological Factors / Q000378:metabolism*; D001920:Bradykinin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors / Q000378:metabolism; D002478:Cells, Cultured; D003331:Coronary Vessels / Q000166:cytology / Q000378:metabolism*; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D007213:Indomethacin / Q000494:pharmacology; D008564:Membrane Potentials / Q000502:physiology; D009532:Nickel / Q000494:pharmacology*; D019335:Nitroarginine / Q000494:pharmacology; D013552:Swine; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology
D001685:Biological Factors; D016861:Cyclooxygenase Inhibitors; D004791:Enzyme Inhibitors; D007211:Indoles; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; C067410:endothelium-dependent hyperpolarization factor; D019335:Nitroarginine; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D009532:Nickel; D000252:Calcium-Transporting ATPases; D001920:Bradykinin; D002118:Calcium; C000543:cyclopiazonic acid; D007213:Indomethacin