Free fatty acids and myocardial function in perfused rat hearts

Mechanical performance and oxygen consumption of isovolumically beating rat hearts perfused with dextrose and with free fatty acids (FFA) have been studied under constant conditions at 37°C. High concentrations of FFA depressed contractility, increased diastolic pressure, and decreased oxygen consumption, but increased the utilization of oxygen for a given tension development. Thus FFA appeared to depress myocardial contractility or oxidative respiration. Conversely, dextrose increased contractility and the addition of insulin increased contractility further. The possibility that the hearts used were oxygen-limited is discussed.