Effect of atrial natriuretic factor on blood pressure, renin, and aldosterone in Goldblatt hypertension

We previously provided evidence that atrial natriuretic factor (ANF) antagonizes angiotensin II-induced vascular contractility and angiotensin II-stimulated aldosterone production by isolated adrenal cells. To examine the importance of these effects in vivo, synthetic ANF (auriculin A) was administered intravenously (2 μg/kg bolus followed by 0.3 μg/kg/min constant infusion) to conscious, unrestrained two-kidney, one-clip and one-kidney, one-clip rats on normal sodium intake and their sham-operated controls. The one-kidney, one-clip rats also were studied on a sodium-deficient diet. Mean blood pressure, plasma renin activity, and plasma aldosterone levels were measured before and after 60-minute infusion. In saralasin-responsive two-kidney, one-clip rats (n = 10), ANF administration reduced blood pressure (from 187 ± 11 [SE] to 153 ± 11 mm Hg; p < 0.001) and plasma aldosterone levels (from 182 ± 61 to 125 ± 60 ng/dl; p < 0.05), while plasma renin activity increased (from 59 ± 16 to 82 ± 20 ng/ml/hr; p < 0.05). Lesser changes in blood pressure occurred in saralasin-nonresponsive two-kidney, one-clip rats (149 ± 10 to 143 ± 8 mm Hg; n = 5), sodium-replete one-kidney, one-clip rats (183 ± 9 to 170 ± 11 mm Hg; n = 9), two-kidney sham-operated rats (122 ± 3 to 115 ± 4 mm Hg; n = 8), and one-kidney sham-operated rats (117 ± 3 to 112 ± 3 mm Hg; n = 7). Control plasma renin and aldosterone levels were not elevated in these latter groups and did not change significantly with ANF administration. In sodium-depleted one-kidney, one-clip rats, which became saralasin responsive, ANF administration significantly reduced blood pressure (from 184 ± 11 to 156 ± 12 mm Hg; n = 8), plasma aldosterone levels (from 286 ± 41 to 179 ± 36 ng/dl), and plasma renin activity (from 69 ± 19 to 44 ± 13 ng/ml/hr). These data indicate that ANF has potent antihypertensive and aldosterone-suppressing effects in vivo, irrespective of induced changes in plasma renin activity. Both the vascular and adrenal effects of ANF appear to be enhanced when the activity of renin-aldosterone system is increased.