Acute cerebrovascular and myocardial ischemia superimposed upon chronically hypertensive and arteriosclerotic male Sprague-Dawley rats.

Repeatedly bred male rats which develop arteriosclerosis spontaneously were subjected to unilateral nephrectomy, 1% saline drinking water, and 2 mg subcutaneous injections of deoxycorticosterone acetate per animal weekly for 7 weeks to induce severe hypertension (+/- 175 mmHg systolic). Acute cerebral ischemia was induced by ligating one carotid artery. Two days later, experimental animals were subjected to acute myocardial ischemia by injecting them subcutaneously with a single dose of isoproterenol (25 mg/100 g body weight). All of the experimental animals died within 4 hours of the injection of isoproterenol. During this same period, blood pressure, body weight, thymus, kidney, and testicular weights were reduced, whereas heart and adrenal gland weights increased markedly. Serum enzymes (CPK, SGOT, and LDH), lipids (triglycerides and free fatty acids), glucose, BUN, and corticosterone rose progressively. Fatty infiltration of the liver, adrenal hyperplasia, myocardial thrombi, renal degenerative changes, and cerebral edema became progressively more severe. A hypothalamic-pituitary-adrenal axis component may be involved in the reaction to the stress of acute cerebral or myocardial ischemia, which is intensified when the two ischemias are combined, and chronic hypertension may exacerbate both.