Inhibitory actions of endothelial products on mechanical and calcium responses in aortic smooth muscle cells.
The effects of endothelial products on intracellular calcium ion concentrations ([Ca2+]i) were investigated in the guinea-pig aorta. The perfusate of bradykinin-stimulated cultured endothelial cells relaxed aortic rings by approximately 70%; it was reduced to approximately 50% by nitroarginine, to approximately 30% in high-K solution and remained unaltered by indomethacin. The perfusate elevated the cyclic GMP content in the muscle, which was inhibited by nitroarginine. In cultured, aortic muscle cells, bradykinin elevated [Ca2+]i with an initial transient and following sustained phase; the former was absent after treatment with cyclopiazonic acid while the latter was abolished in [Ca2+]o-free medium. The perfusate lowered aortic [Ca2+]i, and this action was weakened by nitroarginine and diminished in high-K solution. Therefore, the perfusate reduced aortic [Ca2+]i with and without an increase in cyclic GMP production. These actions were sensitive to nitroarginine and high-K, respectively, suggesting that the perfusate contained at least two relaxants, EDRF and EDHF, with both lowering [Ca2+]i in aortic muscle mainly by inhibiting Ca2+ influx.
Fukuta
H
H
Department of Physiology, Nagoya City University Medical School, Japan.
Miwa
K
K
Hozumi
T
T
Yamamoto
Y
Y
Suzuki
H
H
D000818:Animals; D001011:Aorta / Q000737:chemistry / Q000502:physiology*; D001685:Biological Factors / Q000032:analysis / Q000502:physiology*; D001920:Bradykinin / Q000494:pharmacology; D002118:Calcium / Q000032:analysis*; D002417:Cattle; D002478:Cells, Cultured; D006152:Cyclic GMP / Q000032:analysis; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000737:chemistry*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006168:Guinea Pigs; D007211:Indoles / Q000494:pharmacology; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D009126:Muscle Relaxation / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000737:chemistry / Q000502:physiology*; D009569:Nitric Oxide / Q000032:analysis / Q000502:physiology*; D019335:Nitroarginine / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology
D001685:Biological Factors; D016861:Cyclooxygenase Inhibitors; D004791:Enzyme Inhibitors; D007211:Indoles; D014665:Vasodilator Agents; C067410:endothelium-dependent hyperpolarization factor; D019335:Nitroarginine; D009569:Nitric Oxide; D006152:Cyclic GMP; D001920:Bradykinin; D002118:Calcium; C000543:cyclopiazonic acid; D007213:Indomethacin