Effect of zinc on acute and chronic isoproterenol induced heart injury

Abstract

Hypertensive male rats were injected with single or multiple injections of isoproterenol. Some of the rats were administered zinc parenterally. A significant increase in serum zinc concentration occurred after administration of zinc but not in zinc content of the heart. Acute isoproterenol injection induced a 5-fold increase in calcium content of the heart. Zinc treatment significantly reduced calcium content and increased zinc content of the injured heart. When isoproterenol was injected in rats pretreated and simultaneously administered zinc for a period of 14 days, zinc significantly reduced calcium content, collagen content and size of the necrotic area in the heart. Histopathology of heart of rats treated with both zinc and isoproterenol showed only foci of necrosis replaced with less organized granulation tissue, while isoproterenol alone induced confluent circumferential subendocardial necrosis with mature granulation tissue. The weight of the heart (wet, dry, relative) was not affected by zinc treatment. The weight of the adrenal, significantly increased by isoproterenol, was significantly less in zinc-treated animals. It is concluded that parenteral administration of zinc partially protects the heart against isoproterenol induced myocardial necrosis. Although the mechanism of this effect is still not quite clear, we propose that zinc decreases the isoproterenol-induced influx of calcium into the myocardium, thus lowering the imbalance between heart work and O 2-supply to the cardiac muscle.