title: Effect of adenosine on myocardial oxygen balance.
abstract: The present study was designed to determine the effect of adenosine on oxyhemoglobin equilibrium (P-50) and myocardial oxygen consumption (MVO2) in the isolated supported dog heart preparation perfused at a constant coronary blood flow. Heart rate was controlled at 150 beats/min. A-3-minute intracoronary infusion of adenosine (10, 50 and 100 mug/min) produced significant decreases in MVO2, whereas coronary venous P-50 did not change. Adenosine-5'-monophosphate (5'-AMP) infusion (70 and 140 mug/min) did not produce a significant change in MVO2. Both adenosine and 5'-AMP caused equivalent decreases in coronary artery perfusion pressure and peak left ventricular systolic pressure. Furthermore, adenosine (50 and 100 mug/min) produced a significant decrease in MVO2 of the isolated supported fibrillating heart. These results suggest that the reduction in MVO2 observed with adenosine is not related to coronary vasodilation or to a negative inotropic or chronotropic action. Theophylline (2.5 mg/kg) partially blocked the hemodynamic effects of adenosine while completely abolishing the decrease in MVO2. Neither inosine nor hypoxanthine (50 and 100 mug/min) changed MVO2, P-50 or myocardial hemodynamics. Thus, in addition to its proposed role in coronary blood flow regulation, adenosine appears to exert important effects on myocardial metabolism.
mesh_terms: D000241:Adenosine / Q000494:pharmacology*; D000249:Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D003326:Coronary Circulation / Q000187:drug effects; D004285:Dogs; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D007042:Hypoxanthines / Q000494:pharmacology; D007288:Inosine / Q000494:pharmacology; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects; D009206:Myocardium / Q000378:metabolism*; D010101:Oxygen Consumption / Q000187:drug effects*; D013806:Theophylline / Q000494:pharmacology; D014693:Ventricular Fibrillation / Q000378:metabolism
chemical_list: D007042:Hypoxanthines; D000249:Adenosine Monophosphate; D007288:Inosine; D013806:Theophylline; D000241:Adenosine