Myocardial uptake of free fatty acids and carbohydrates after beta adrenergic blockade

Abstract

The myocardial extraction and usage of free fatty acids, glucose, lactate and pyruvate as well as some hemodynamic parameters have been studied in anesthetized dogs in a basal state and after beta adrenergic blockade and blood-letting. Under these conditions a noticeable reduction of cardiac work and coronary flow was observed. After beta blockade, myocardial consumption of oxygen and free fatty acids decreased significantly; the myocardial oxygen extraction ratio of free fatty acids and the coronary A-V difference declined, whereas utilization of carbohydrates did not change. After bleeding, the uptake of oxygen and free fatty acids by the myocardium decreased to a lesser extent than after beta blockade, whereas the myocardial oxygen extraction ratio of free fatty acids and the coronary A-V difference rose; cardiac consumption of glucose, lactate and pyruvate did not show any significant change. The results obtained suggest that there is some specific and positive adrenergic action on myocardial utilization of free fatty acids. This action can be inhibited by beta blockers.