Myocardial necrosis induced by breeding in stroke-prone/SHR.

Virgin and breeder, spontaneously hypertensive and stroke prone rats (SHR/SP) were observed from weaning until 130 +/- 10 days of age. Blood pressure rose rapidly, reaching 230--240 mm Hg. After the birth of the second litter of pups, male and female breeders began to die suddenly, due to myocardial necrosis and congestive heart failure. At autopsy, the brains of virgin and breeder SHR/SP were swollen but were free of any pathologic changes. There were no significant alterations in the blood chemistry of virgin rats but breeder SHR/SP had super-normal enzyme levels, CPK, SGOT, SGPT and LDH, hyperglycemia, hyperlipidemia, and hypersecretion of corticosterone. Breeder SHR/SP developed PAN-like lesions of the mesenteric arcades and adrenal cortex along with severe fibrino-hyalin lesions of the testicular and ovarian arteries. It is suggested that alterations in hypothalamic-pituitary-adrenal function associated with the reproductive effort conditioned these SHR/SP to develop myocardial necrosis rather than stroke and the development of unusual hypertensive arteriopathy.