Vascular lesions and angiotensin in malignant hypertension in the absence of vasopressin.

1. Vasopressin deficient homozygous Brattleboro rats develop malignant renal hypertension following complete aortic-ligature between the renal arteries. 2. This form of hypertension is associated with high plasma renin activity (PRA) and plasma angiotensin II (AII) levels and a high incidence of the specific vascular lesions of fibrinoid necrosis in both Brattleboro and Long-Evans rats. 3. The levels of PRA and AII in the malignant hypertensive Brattleboro rats were not different from those in Long-Evans rats with malignant hypertension. 4. No compensation by the renin-angiotensin system therefore could be demonstrated for the lack of vasopressin in malignant hypertensive Brattleboro rats. 5. Vasopressin does not appear to be essential as a pressor hormone in the development of malignant renal hypertension and fibrinoid can occur in the absence of vasopressin.