Effect of propionyl carnitine on cardiac energy metabolism evaluated by the release of purine catabolites.

The assessment of purine release in perfusion fluid is a new method (Zucchi et al.) which allows a continuous evaluation of energy metabolism in isolated perfused rat heart. Purine release in fact is related to the imbalance between ATP formed and utilized in myocytes. With this method we have investigated the effect of propionyl carnitine, carnitine and propionate on the working heart. The presence of millimolar concentrations of propionyl carnitine decreases purine release and improves cardiac performance as measured by cardiac output and double product (product of heart rate and aortic systolic pressure). Propionate has no effect, while carnitine slightly decreases purine release. The property shown by propionyl carnitine in decreasing the imbalance between ATP production and utilization and in improving cardiac performance is due to its ability to improve the energy metabolism of cardiomyocytes. This compound supplies oxidizable substrates and intermediates to the tricarboxylic acid cycle. In the presence of propionyl carnitine the myocardium therefore responds better to the sudden requirements of overwork and shows better functional efficiency for longer periods.