Myocardial Metabolism of Exogenous Plasma Triglycerides in Resting Man

A nephelometric technique has been used to measure concentrations of exogenous triglyceride in arterial and coronary sinus blood. The technique has been validated in a comparison of estimated arterial‐coronary sinus differences with those obtained by the chemical determination of total plasma triglyceride. Statistically significant disappearances of exogenous triglyceride across the coronary circulation were observed both during the lipaemia after a fatty meal and during the i.v. infusions of a fat emulsion and glucose solution. The uptake of exogenous triglycerides, about 6% of the arterial concentration, could supply about 50% of the heart's energy requirements. Significant productions of glycerol across the coronary circulation were found in both types of fed state in amounts corresponding to a complete lipolysis of 25–50% of the exogenous triglyceride removed. Net myocardial extractions of free fatty acids were less than in a previous study in the fasting state, which may mean that all triglyceride fatty acid released by lipolysis is not taken up by the myocardium. Also, myocardial extraction of blood glucose was less in the oral fed state than in a previous study in the fasting state.