Abstract
Propionyl-L-carnitine (PLC), a natural short-chain derivative of L-carnitine, has been tested in this study as a potential protective agent against adriamycin (ADR)-induced cardiotoxicity in isolated rat heart myocytes and mitochondria. In cardiac myocytes, ADR (0.5 mM) caused a significant (70%) inhibition of palmitate oxidation, whereas, PLC (5 mM) induced a significant (49%) stimulation. Addition of PLC to ADR-incubated myocytes induced 79% reversal of ADR-induced inhibition of palmitate oxidation. In isolated rat heart mitochondria, ADR produced concentration-dependent inhibition of both palmitoyl-CoA and palmitoyl-carnitine oxidation, while PLC caused a more than 2.5-fold increase in both substrates. Preincubation of mitochondria with 5 mM PLC caused complete reversal of ADR-induced inhibition in the oxidation of both substrates. Also ADR induced concentration-dependent inhibition of CPT I which is parallel to the inhibition of its substrate palmitoyl-CoA. In rat heart slices, ADR induced a significant (65%) decrease in adenosine triphosphate (ATP) and this effect is reduced to 17% only by PLC. Results of this study revealed that ADR induced its cardiotoxicity by inhibition of CPT I and beta-oxidation of long-chain fatty acids with the consequent depletion of ATP in cardiac tissues, and that PLC can be used as a protective agent against ADR-induced cardiotoxicity.