Abstract-Chronic treatment of saline-drmkmg stroke-prone spontaneously hypertensive rats (SHRSP) with agents that interfere with the formation or actions of angotensm II (Ang II) prevents the development of stroke and renal vascular damage Ang II, m addltlon to its direct vascular effects, stimulates the synthesis and release of aldosteroneTo assess the role of aldosterone m the development of pathologc changes m these rats, we implanted time-release pellets containing 200 mg of the mmeralocortlcold receptor antagomst, spu-onolactone, mto 14 SHRSP at 7 5 weeks of age Eight SHRSP httermates received placebo pellets Over the period of study (3 to 4 weeks), systolic blood pressure (SBP) (PRA) and aldosterone as independent nsk factors for heart attack and stroke ' They found that among the patients who developed strokes and myocardlal mfarctlons, all had normal or high PRA, and aldosterone secretlon Previous studies by our group and others have provided expenmental evidence to support a role for the renm-angotensm-aldosterone system (RAAS) m the development of vascular qury, as angotensm converting enzyme (ACE) mhlbltors2-6 and Ang II receptor antagonlsts7-9 prevented the development of stroke and malignant nephrosclerosls m SHRSP Since these studies were conducted m salt-loaded SHRSP, which respond to these agents with nummal blood pressure lowermg, they provided evidence for a pathophyslolog& role for Ang II m the development of vascular lesions of malignant nephrosclerosls independent of severely elevated blood pressure Consistent with a role for Ang II was the finding that SHRSP display a paradoxical increase m PRA with rime, despite continued salt-loading 3 9,'" Although Ang II stimulates the synthesis and release of aldosterone," " m addmon to its direct vascular actions, a role for mmeralocortlcolds m the pathology of SHRSP

In patients with CAD, a low BP (<110-120/<60-70 mmHg) portends an increased risk of future cardiovascular events (except stroke).

No abstract

Abstract-Stroke-prone spontaneously hypertensive rats (SHRSP) on 1% NaCl drinking solution and Stroke-Prone Rodent Diet develop severe hypertension and glomerular and vascular lesions characteristic of thrombotic microangiopathy seen in malignant nephrosclerosis. We recently reported that spironolactone, a mineralocorticoid receptor antagonist, markedly reduced proteinuria and malignant nephrosclerotic lesions in these animals. This observation, together with our previous findings that angiotensin-converting enzyme inhibitors prevent the development of vascular damage, suggests that mineralocorticoids, as part of the renin-angiotensin-aldosterone system, play a pathophysiological role in this model. In the present study, we examined whether chronic (2-week) infusion of aldosterone can reverse the renal vascular protective effects of captopril in SHRSP. SHRSP received vehicle (nϭ8); captopril alone (50 mg ⅐ kg; or captopril and aldosterone at 20 (nϭ6) or. Systolic blood pressure was markedly elevated in all groups. Vehicle-and aldosterone-infused SHRSP developed severe proteinuria and comparable degrees of renal injury (21Ϯ3% and 29Ϯ3%, respectively) manifested as thrombotic and proliferative lesions in the arterioles and glomeruli. Captopril treatment reduced plasma aldosterone levels concomitant with marked reductions in proteinuria and the absence of histologic lesions of malignant nephrosclerosis. Aldosterone substitution at 20 or 40 g ⅐ kg Ϫ1 ⅐ d Ϫ1 in captopril-treated SHRSP resulted in the development of severe renal lesions (16Ϯ3% and 21Ϯ2%, respectively) and proteinuria comparable with that observed in SHRSP given either aldosterone or vehicle alone. These findings support a major role for aldosterone in the development of malignant nephrosclerosis in saline-drinking SHRSP, independent of the effects of blood pressure. Key Words: hypertension Ⅲ kidney Ⅲ malignant nephrosclerosis Ⅲ captopril Ⅲ aldosterone T he participation of the renin-angiotensin-aldosterone system (RAAS) in the development of hypertensive vascular injury has been widely demonstrated. 1 Numerous studies with angiotensin-converting enzyme (ACE) inhibitors and with angiotensin (Ang) II receptor antagonists have clearly identified Ang II as a major factor responsible for the development of end-organ damage in hypertensive vascular disease. However, mineralocorticoids may also play an important role, because animals with deoxycorticosterone acetate (DOCA)-salt hypertension typically develop severe vascular pathology, and resultant malignant nephrosclerosis, myocardial necrosis, and stroke, 2-5 despite low levels of plasma renin activity. 2,5,6 The renal lesions that develop in DOCA-salt hypertensive rats are characterized by fibrinoid necrosis of blood vessels and proliferative arteriopathy 2-4 and are very similar to those seen in stroke-prone spontaneously hypertensive rats (SHRSP) receiving a high sodium chloride diet 7-11 and in rats with Ang II-salt-induced hypertension. 12 We have shown that chronic administration of agents that inter...

No abstract