| pubmed-article:4003303 | pubmed:abstractText | Effects of collagen-activated washed rabbit platelets on coronary arteries with and without intact endothelium were studied in a supported rabbit heart preparation using a perfluorocarbon (FC-43) as perfusate. The vascular diameter of obtuse marginal coronary arteries was determined by means of gated color arteriography (injection of patent blue dye). Endothelial denudation of the obtuse marginal artery was accomplished by scraping the lumen with a roughened plastic tubing. Injection of washed platelets (10 ml with about 500,000 platelets/microliters) not treated with collagen failed to constrict coronary arteries either with intact or denuded endothelium. In contrast, injection of platelet suspension immediately after activation with collagen caused vasoconstriction of denuded obtuse marginal coronary arteries in 10 of 14 cases. In 6 preparations occlusion was complete, lasting up to 16 minutes. In arteries with intact endothelium, no coronary vasoconstriction occurred. In hearts with coronary artery spasm, total coronary vascular resistance increased significantly. This study furnishes additional evidence that endothelial lesions are a contributory factor for large coronary artery spasm and that endothelial cells possess a protective function against vasoconstrictor substances released from aggregating platelets. | lld:pubmed |
