Carnitine Promotes Heat Shock Protein Synthesis in Adriamycin-induced Cardiomyopathy in a Neonatal Rat Experimental Model

In order to evaluate carnitine protective strategy and its relationship with heat shock protein induction, female Sprague-Dawley neonatal rats, body weight 40 g, were randomized into four groups: control, adriamycin, carnitine and carnitine–adriamycin. Adriamycin was injected i.v. at a dose of 27 mg/kg (0.1 ml). Carnitine was administered i.v. (20 mg/0.1 ml) before each subdose of adriamycin and thenper os(180 mg/kg) daily for 12 weeks. Body weight was recorded weekly. Ventricular wall thickness and cellular damage percentage were morphometrically and ultrastructurally determined, respectively. The determinations were realized monthly until the third month after treatment. The heat shock protein 25 content in the supernatant of the homogenized heart tissue was determined by Western blot analysis. Eight and 12 weeks after treatment, body weight and ventricular wall thickness decreased much more in adriamycin groups than in control and carnitine ones. At the same time, electron microscopic analysis of adriamycin left ventricular wall samples showed loss of myofibrils, swollen mitochondria and vacuoles. Carnitine–adriamycin treated rats resemble control groups more than adriamycin treated samples. Moreover,de-novosynthesis of heat shock protein was three times more induced in carnitine–adriamycin rats than in adriamycin ones. Carnitine may enhance the cell-protecting mechanism based on an induction of shock protein, and this first cellular response could reduce the severity of late adriamycin-cardiomiopathy.