Free radical scavenging is involved in the protective effect of l-propionyl-carnitine against ischemia-reperfusion injury of the heart

Abstract

l-Propionyl-carnitine is known to improve the recovery of myocardial function and metabolic parameters reduced in the course of ischemia-reperfusion of the heart. The mechanism of this protective effect of l-propionyl-carnitine is not fully understood. The purpose of this study was to elucidate the effects of l-propionyl-carnitine in Langendorff perfused rat hearts subjected to 40 min of ischemia followed by 20 min of reperfusion. We tested the hypothesis that l-propionyl-carnitine suppresses generation of oxygen radicals and subsequent oxidative modification of myocardial proteins during reperfusion. Our data show that the protective effect of l-propionyl-carnitine in the course of ischemia-reperfusion is highly significant in terms both of mechanical properties of the heart (developed pressure) and of high-energy phosphates (ATP, creatine phosphate). Myocardial creatine phosphokinase (CPK) activity decreased in the course of the reperfusion period. The loss of CPK activity was partially prevented by l-propionyl-carnitine. Two other effects were observed when l-propionyl-carnitine was present in the perfusion solution: (i) the reperfusion-induced sharp increase in oxidative protein modification was completely prevented as detected by the formation of protein carbonyls, and (ii) generation of hydroxyl radicals was significantly inhibited as detected by the formation of the adducts with the spin trap 5,5-dimethyl-1-pyrroline-1-oxide. We conclude that the protective effect of l-propionyl-carnitine against ischemia-reperfusion injury of the heart is at least due in part to its ability to suppress the development of oxidative stress and free radical damage.