Myocardial infarction in spontaneously hypertensive rats with superimposed adrenal-regeneration hypertension.

The elevated blood pressure of spontaneously hypertensive rats (SHR) was further exacerbated by subjecting these animals to surgically induced adrenal-regeneration hypertension (ARH). When chronic abnormally high blood pressure had been in effect for 12 weeks, the animals were subjected to an acute and massive myocardial infarction with isoprenaline. Hypertensive but intact SHR survived better than ARH-treated animals. Circulating enzyme (CPK, SGOT, SGPT and LDH), lipid and glucose levels and BUN manifested much greater excursions commensurate with more extensive myocardial infarction in ARH-treated than in intact SHR. ARH-treated SHR displayed a high incidence of atrial and ventricular thrombi associated with frequent left ventricular aneurysm formation. It is suggested that the more extensive myocardial connective tissue and ground-substance degeneration in ARH-treated SHR is due to the impoverished steroidogenic capacity of their regenerated adrenal glands.