Abstract
RNA content in the heart muscle cells of the adrenalectomized rats and those with aortic constriction was measured by microspectrophotometry. In the adrenalectomized rats, the RNA content decreased about 32% below that of the intact control rats by 7 days after operation. On the other hand, it decreased more abruptly in the adrenalectomized rats with aortic constriction. These results suggested that in the adrenalectomized rats, hypoplasia of the heart was caused by reduction of RNA content and myocardial compensatory hypertrophy was never induced even by overloading to the heart. The fact that the reduction of RNA content preceded the decrease of the heart weight per 100 g body weight suggests that in the cases of sudden unexpected death by unknown cause, the measurement of RNA content of heart muscle cells may by a clue to judge whether the cause of death is concerned with the heart or not.
