Role of smooth muscle cells on endothelial cell cytosolic free calcium in porcine coronary arteries.
We tested the hypothesis that the cytosolic free calcium concentration in endothelial cells is under the influence of the smooth muscle cells in the coronary circulation. In the left descending branch of porcine coronary arteries, cytosolic free calcium concentration ([Ca(2+)](i)) was estimated by determining the fluorescence ratio of two calcium probes, fluo 4 and fura red, in smooth muscle and endothelial cells using confocal microscopy. Acetylcholine and potassium, which act directly on smooth muscle cells to increase [Ca(2+)](i), were found to indirectly elevate [Ca(2+)](i) in endothelial cells; in primary cultures of endothelial cells, neither stimulus affected [Ca(2+)](i), yet substance P increased the fluorescence ratio twofold. In response to acetylcholine and potassium, isometric tension developed by arterial strips with intact endothelium was attenuated by up to 22% (P < 0.05) compared with strips without endothelium. These findings suggest that stimuli that increase smooth muscle [Ca(2+)](i) can indirectly influence endothelial cell function in porcine coronary arteries. Such a pathway for negative feedback can moderate vasoconstriction and diminish the potential for vasospasm in the coronary circulation.
Budel
S
S
Department of Zoology and Animal Biology, Sciences III, 1211 Geneva 4, Switzerland.
Schuster
A
A
Stergiopoulos
N
N
Meister
J J
JJ
Bény
J L
JL
D000109:Acetylcholine / Q000494:pharmacology; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D001920:Bradykinin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D003331:Coronary Vessels / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005456:Fluorescent Dyes; D066298:In Vitro Techniques; D007537:Isometric Contraction / Q000187:drug effects / Q000502:physiology; D018613:Microscopy, Confocal; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology; D013373:Substance P / Q000494:pharmacology; D013552:Swine; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology
D000318:Adrenergic beta-Agonists; D005456:Fluorescent Dyes; D013373:Substance P; D000109:Acetylcholine; D011188:Potassium; D001920:Bradykinin; D002118:Calcium