Effects of catecholamines on the coronary circulation in the Langendorff-type transplanted dog heart.

Intracoronary administration of isoprenaline, adrenaline, and the noradrenaline in the Langendorff-type transplanted dog heart transiently decreased coronary blood flow measured from the inflow vessel; flow then increased. The reduction in coronary flow coincided with increased myocardial contractility and was prevented by keeping the left ventricle empty. Propranolol prevented changes in flow and contractility. It is concluded that positive inotropic changes result in the ejection of accumulated Thesbesian flow from the ventricle and affect coronary flow measurements and that the interpretation of flow changes requires a steady state.