Alteration in oxyhemoglobin equilibrium (P-50) and myocardial oxygen consumption (MVO2) by nitroglycerin (GTN).
In the isolated supported dog heart preparation perfused at a constant coronary blood flow, heart rate and left ventricular systolic pressure were not changed significantly by a 3-minute intracoronary infusion of nitroglycerin (5 and 10 mug/min). Nitroglycerin produced a significant increase in coronary venous pO2 and coronary venous P-50. These effects were accompanied by a significant decrease in myocardial oxygen consumption (MVO2). An infusion of dipyridamole (25 and 50 mug/min) did not produce significant changes in coronary venous pO2, P-50 or MVO2. Both drugs produced equivalent decreases in coronary artery perfusion pressure which suggests that the increase in coronary venous P-50 or reduction in MVO2 observed with nitroglycerin is not related to coronary vasodilation. The increase in P-50 induced by nitroglycerin was not accompanied by an increase in total erythrocytic 2,3-diphosphoglycerate and was not observed in vitro. The increase in P-50 produced by nitroglycerin provides a potential reservoir of readily diffusible oxygen that may be utilized during periods of myocardial hypoxia.
D000818:Animals; D003331:Coronary Vessels / Q000502:physiology; D004163:Diphosphoglyceric Acids / Q000097:blood; D004176:Dipyridamole / Q000494:pharmacology; D004285:Dogs; D005260:Female; D006454:Hemoglobins / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D005996:Nitroglycerin / Q000494:pharmacology*; D010101:Oxygen Consumption / Q000187:drug effects*; D010108:Oxyhemoglobins / Q000378:metabolism*; D010477:Perfusion
D004163:Diphosphoglyceric Acids; D006454:Hemoglobins; D010108:Oxyhemoglobins; D004176:Dipyridamole; D005996:Nitroglycerin