Forebrain contributions to one-kidney renal hypertension in the rabbit

Electrolytic lesions were placed along the anteroventral wall of the third cerebral ventricle (AV3V region) in 10 albino rabbits (AV3V-X), and sham lesions were produced in 10 additional rabbits (SHAM). Two to 3 weeks later, all rabbits underwent unilateral nephrectomy and renal artery stenosis (clip I.D. = 0.508 mm). During a 1-week control period, and for 4 weeks after renal artery stenosis, measurements were made of mean arterial pressure (MAP), heart rate, body fluid compartment volumes, plasma electrolytes, and daily sodium, potassium, and water balances. Four weeks after renal artery stenosis (RAS), cardiovascular responses to norepinephrine (NE), angiotensin II (AII), saralasin, and autonomic blockade were obtained in the conscious animals. In SHAM rabbits, MAP rose from 77 to 117 mm Hg 4 weeks after RAS. In AV3V-X rabbits, MAP rose from 77 to only 92 mm Hg 4 weeks after RAS. Body fluid compartment volumes, plasma electrolytes, and fluid, sodium, and potassium balances showed similar modest changes in both groups of rabbits. Neither saralasin infusion nor autonomic blockade caused significantly different changes in MAP between SHAM and AV3V-X rabbits 4 weeks after RAS. However, pressor responses to both NE and AII were significantly less in AV3V-X rabbits at this time. It is concluded that one-kidney, one clip renal hypertension involves activation of neurohormonal pressor mechanisms originating in the forebrain, and that the expression of these pressor mechanisms in part includes an increase in cardiovascular reactivity.