title: Regulation of myocardial oxygen consumption by perfusion pressure in isolated fibrillating canine heart.
abstract: In order to evaluate whether perfusion pressure or coronary flow affect myocardial oxygen metabolism, oxygen consumption of the isolated fibrillating blood-perfused canine heart was investigated at perfusion pressures of 100, 150, and 200 mm Hg. To obtain different coronary flow rates at a given coronary perfusion pressure, alpha-adrenergic blockade by phenoxybenzamine (10 mg/kg b.w.) was applied, resulting in an increase in coronary flow and a decrease in myocardial oxygen extration. Myocardial oxygen consumption was increased by elevation of perfusion pressure in both the control and phenoxybenzamine-pretreated group. At the same level of perfusion pressure there was no significant difference between the oxygen consumption of control and phenoxybenzamine-pretreated preparations. It can be concluded that in the isolated fibrillating canine heart oxygen consumption is primarily regulated by perfusion pressure, and is independent from coronary blood flow.
mesh_terms: D000818:Animals; D003326:Coronary Circulation / Q000187:drug effects; D004285:Dogs; D006321:Heart / Q000187:drug effects; D009206:Myocardium / Q000378:metabolism*; D010101:Oxygen Consumption / Q000187:drug effects; D010477:Perfusion; D010643:Phenoxybenzamine / Q000494:pharmacology
chemical_list: D010643:Phenoxybenzamine