Modulation of renin secretion by atrial natriuretic factor prohormone fragment 31-67

Background: Earlier studies have indicated that the atrial natriuretic fact or prohormone fragment 31-67 (Pro ANF(31-67)) has important effects for the promotion of sodium excretion and vasodilation in several animal species. However, the mechanisms for the natriuretic actions of Pro ANF(31-67) are n ot completely defined. In the present study, the effects of synthetic Pro A NF(31-67) on renin secretion were examined in sodium-depleted, anesthetized dogs with a single intact kidney (n = 5). Methods: After 3 20-minute contr ol renal clearance periods, synthetic dog Pro ANF(31-67) was given intraren ally at a sustained dose of 0.03 mu g/kg/min for 3 20-minute experimental i ntervals, and after discontinuation of the peptide infusion, 3 final 20-min ute recovery periods were determined. Results: Sustained intrarenal infusio ns of the Pro ANF(31-67) produced striking decrements (p<0.05) in renin sec retion, from a control value of 1418 +/- 243 to 401 +/- 223 ng of angiotens in l/min. This 66% fall in renin secretion was associated with significant (P < 0.05) increases in creatinine clearance (40%), renal blood flow (8%), urine flow (50%), and sodium excretion (17%). Conclusions: it is suggested that this inhibition of renin secretion was mediated, at least in part, in response to a ProANF(31-67)-induced increment in the sodium load delivered to the macula densa. An interaction of the peptide with the renal vascular receptor for suppression of renin release is also possible. ProANF(31-67) m ay represent an important hormonal mechanism involved in the regulation of bodyfluid balance.