title: A stop-flow study of intrarenal effects of atrial natriuretic factor.
abstract: We performed paired series of stop-flow studies on six mongrel dogs to determine a possible nephron site of action of synthetic atrial natriuretic factor (ANF). The initial free-flow response to intrarenal infusion of 5 micrograms/min of synthetic ANF into mannitol-expanded dogs resulted in an increased urine flow rate (6.81 +/- 0.88 to 9.00 +/- 1.17 ml/min, P less than 0.05) and a 40% increase in sodium excretion (496 +/- 110 to 694 +/- 166 meq/min, P less than 0.025) when compared to paired control periods. Renal blood flow did not change, but the glomerular filtration rate increased 4% (47 +/- 5 to 49 +/- 6 ml/min, P less than 0.05). The filtered load of sodium increased 4% (P less than 0.05), and the fractional sodium excretion increased by 35% (P less than 0.01). Stop-flow experiments showed no difference in tubular sodium concentration or in the fractional sodium-to-inulin ratio at the nadir of sodium concentration, suggesting that no differences existed in distal tubular sodium handling. Further, no apparent differences were detected in collections representing the more proximal portions of the nephron. While we were able to demonstrate marked natriuresis in response to synthetic ANF, no tubular effect was discernible, and the natriuresis obtained appears to be predominantly a function of hemodynamic effects.
mesh_terms: D000818:Animals; D009320:Atrial Natriuretic Factor / Q000494:pharmacology*; D004231:Diuresis / Q000187:drug effects; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D005919:Glomerular Filtration Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D007444:Inulin / Q000097:blood / Q000652:urine; D007668:Kidney / Q000098:blood supply / Q000187:drug effects*; D009318:Natriuresis / Q000187:drug effects; D009399:Nephrons / Q000187:drug effects; D011188:Potassium / Q000652:urine; D012964:Sodium / Q000652:urine
chemical_list: D009320:Atrial Natriuretic Factor; D007444:Inulin; D012964:Sodium; D011188:Potassium