Systemic stress in the production of cardiac thrombosis in hypercholesterolaemic rats

Abstract

An experimental study to elucidate the effects of feeding a high fat diet, hypercholesterolaemia and superadded acute and chronic stress on the production of cardiac thrombosis was carried out in rats. The high fat diet contained 25 percent butter rat providing 45 percent calories from fat which produced significant increase of serum cholesterol and other lipids. Acute stress was induced by two injections of adrenaline on a single day which caused a marked transient alteration of haemodynamics. Chronic stress was of two types, physical and metabolic. The physical stress was induced by repeated exposure of the rats to electric shock or roller drum exercise, while metabolic stress was caused by repeated injection of ACTH. Rats of both acute and chronic stress groups showed variable degree of medial degeneration, hyaline and fibrinoid intimal deposits and calcification in coronary arteries. Cardiac thrombi were seen in 30 percent animals subjected to adrenaline shock. Among the chronic stress procedure 17 percent rats exposed to electric shock and only one rat of the ACTH group developed cardiac thrombosis but no thrombus was detected in those exposed to roller drum exercise. The myocardium showed patchy necrosis with or without calcification, Spontaneous mortality was maximum following acute adrenaline shock (25 %) while electric shock caused mortality in 17 percent animals. The other procedures did not lead to spontaneous mortality. This study highlights the significant role of high fat intake, hypercholesterolaemia and systemic stress in the pathogenesis of acute cardiac thrombosis and myocardial necrosis/infarction.