Vitamin D-induced myocardial lesions and the protection by carbocromen.

Effects of high doses of vitamin D on rat hearts were investigated 72 h after the administration of 500 000 U/kg. Histological examination showed disseminated focal necrosis with reactive round cell and granulocytic infiltration in the heart. The calcium content was increased by about 70%. These findings indicate vitamin D-induced myocardial lesions. Heart mitochondrial calcium binding and uptake activities were lower than in control animals. Na+-K+-ATPase activity of heart washed particles was reduced by the treatment with vitamin D whereas neither calcium binding and uptake activities of cardiac sarcoplasmic reticulum nor myofibrillar ATPase activity were affected. Carbocromen (20 and 100 mg/kg/d) treatment reduced vitamin D-induced decreases in mitochondrial calcium accumulating ability and Na+-K+-ATPase activity of heart washed particle, suggesting a beneficial effect of carbocromen against vitamin D-induced cardiac injury.