AJP - Heart and Circulatory Physiology, Vol 270, Issue 6 2038-H2049, Copyright © 1996 by American Physiological Society

ARTICLES

CPA induces a sustained increase in [Ca2+]i of endothelial cells in situ and relaxes porcine coronary artery

Y. Higuchi, J. Nishimura, S. Kobayashi and H. Kanaide
Division of Molecular Cardiology, Faculty of Medicine, Kyushu University, Fukuoka, Japan.

Using fura 2 fluorometry, we investigated the effect of cyclopiazonic acid (CPA), an inhibitor of Ca2+ pump adenosinetriphosphatase of the endoplasmic reticulum, on cystosolic Ca2+ concentration ([Ca2+]i) and tension in porcine aortic valvular endothelial cells and coronary arterial strips with endothelium. In normal physiological salt solution, CPA induced a sustained increase in [Ca2+]i in the valvular strips, whereas in Ca(2+)-free physiological salt solution, CPA elicited a transient elevation of [Ca2+]i. CPA(30 microM) relaxed coronary strips with endothelium precontracted by 100 nM U-46619; this relaxation was partially inhibited by N omega-nitro-L-arginine (100 microM). These results indicate that the CPA-induced increase in [Ca2+]i depends on the Ca2+ release and the Ca2+ influx in the endothelial cells in situ and that the CPA-induced endothelium-dependent decreases in [Ca2+]i and tension in the smooth muscle are due to the combined effect of N omega-nitro-L-arginine-sensitive and -resistant factors.

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