Attempted prevention of arteriolar lesions in accelerated rat hypertension by immunosuppression.

Reasons are given for suspecting that one component in the injury to small arteries and arterioles in accelerated hypertension may be an immunological mechanism. To test this hypothesis, rats were subjected to a deoxycortone/unilateral nephrectomy/salt load regime and simultaneously treated with one of three immunosuppressive procedures: cyclophosphamide, whole-body X-irradiation or rabbit anti-rat lymphocytic serum (ALS). Histological evidence of a depressive effect on the lymphoreticular tissues was obtained but interference with the normal development of arterial and arteriolar necrosis and of plasmatic vasculosis varied. ALS displayed no protective effect whatever. Cyclophosphamide interfered with the development of hypertensive vascular lesions but caused, by itself, a high mortality among non-hypertensive control animals. X-irradiation prevented hypertensive arteriolar injury but probably exerted this effect by an action distinct from blood pressure since animals so treated developed marked left ventricular hypertrophy, perhaps due to the combined hypertension-provoking insults of deoxycortone and irradiation.