Using fura 2 fluorometry, we investigated the effect of cyclopiazonic acid (CPA), an inhibitor of Ca2+ pump adenosinetriphosphatase of the endoplasmic reticulum, on cytosolic 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 Ca2+- free physiological salt solution, CPA elicited a transient elevation of [Ca2+](i). CPA (30 μM) relaxed coronary strips with endothelium precontracted by 100 nM U-46619; this relaxation was partially inhibited by N(ω)-nitro-L-arginine (100 μM). 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(ω)-nitro-L-arginine-sensitive and -resistant factors.
|Journal||American Journal of Physiology - Heart and Circulatory Physiology|
|Issue number||6 39-6|
|Publication status||Published - Jun 1 1996|
All Science Journal Classification (ASJC) codes
- Cardiology and Cardiovascular Medicine
- Physiology (medical)