title: Prostacyclin produced by the pericardium and its influence on coronary vascular tone.
abstract: To determine the influence of pericardial fluid prostacyclin on coronary blood flow, the latter was measured in the circumflex artery of anesthetized dogs. Intraaortic infusions of angiotensin II (25 ng . kg-1 . min-1) reduced blood flow and released prostacyclin into pericardial fluid. Epicardial and pericardial superfusion with indomethacin (1 micrograms/ml) abolished prostacyclin release and significantly increased the coronary vasoconstrictor effect of angiotensin II; this treatment did not appear to affect vascular synthesis of prostacyclin. Pericardial prostacyclin may modulate the coronary vasoconstrictor effect of angiotensin, but its general role as a regulator of coronary vascular resistance is probably limited. A more important effect of pericardial prostacyclin may be exerted on the large coronary vessels in the epicardial surface. Release of prostacyclin into pericardial fluid represents a potential mechanism for opposing coronary vasospasm, especially if platelet activation is found to be a contributory factor in vasotonic angina pectoris.
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001095:Arachidonic Acids / Q000378:metabolism; D002417:Cattle; D003326:Coronary Circulation / Q000187:drug effects; D003327:Coronary Disease / Q000503:physiopathology; D003331:Coronary Vessels / Q000187:drug effects / Q000502:physiology*; D004285:Dogs; D011464:Epoprostenol / Q000096:biosynthesis*; D007213:Indomethacin / Q000494:pharmacology; D009129:Muscle Tonus / Q000187:drug effects; D010490:Pericardial Effusion / Q000502:physiology; D010496:Pericardium / Q000378:metabolism*; D011453:Prostaglandins / Q000096:biosynthesis*; D051381:Rats; D014664:Vasodilation / Q000187:drug effects
chemical_list: D001095:Arachidonic Acids; D011453:Prostaglandins; D000804:Angiotensin II; D011464:Epoprostenol; D007213:Indomethacin