In stroke-prone spontaneously hypertensive rats (SHRSP), renal vascular injury causing proteinuria and malignant nephrosclerotic lesions were markedly reduced by treatment with spironolactone, an aldosterone receptor blocker. The effect of spironolactone alone was comparable to effect of treatment with captopril, an ACE-inhibitor. In further studies Rocha et al had shown that the ameliorating effect of ACE-inhibition in the SHRSP rats could be fully reversed by infusion of aldosterone, suggesting a major role for aldosterone in the vascular injury in these rats as well. Importantly the deleterious effect of aldosterone and the protective effect of spironolactone against end organ damage in SHRSP rats appeared to be independent of the blood pressure effects.