Modulation of the Natriuretic Response to Atrial Natriuretic Peptide by Alterations in Peritubular: Starling Forces in the Rat

• Published in: Circulation research Vol. 59; no. 6; pp. 605 - 611
• Main Authors: Mendez, Ramon E, Dunn, B Rentz, Troy, Julia L, Brenner, Barry M
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD American Heart Association, Inc 01.12.1986; Lippincott
• Subjects: Angiotensin II - pharmacology; Animals; Atrial Natriuretic Factor - pharmacology; Biological and medical sciences; Blood Pressure - drug effects; Blood vessels and receptors; Fundamental and applied biological sciences. Psychology; Glomerular Filtration Rate - drug effects; Hydrostatic Pressure; Inulin - metabolism; Male; Natriuresis - drug effects; Osmotic Pressure; Peptide Fragments - pharmacology; Potassium - metabolism; Rats; Rats, Inbred Strains; Renal Circulation - drug effects; Sodium - metabolism; Vertebrates: cardiovascular system; Hormone; Rat; Rodentia; Oncotic pressure; Kidney; Vertebrata; Regulation(control); Mammalia; Natriuretic hormone; Blood vessel; Arterial pressure; Blood capillary; Circulatory system; Hemodynamics
• ISSN: 0009-7330; 1524-4571
• DOI: 10.1161/01.RES.59.6.605

The mechanisms underlying the natriuretic response to infusions of atrial natriuretic peptide (ANP) remain incompletely defined. By acting as renal vasodilators, atrial peptides may serve to alter peritubular capillary physical forces and favor a decrease in tubule solute reabsorption. Therefore, we studied the effects of known modifiers of intrarenal Starling forces on the natriuresis induced by infusion of intravenous hANP [4–28] (0.5 μg/kg/min) in anesthetized, euvolemic Munich-Wistar rats. In the first series of studies, infusion of ANP resulted in a significant natriuresis, diuresis, and increase in inulin clearance and in a slight fall in systemic arterial pressure, as compared to vehicle infusion. Subsequent elevation of renal perfusion pressure by superimposition of angiotensin II infusion (0.1–0.2 μg/kg/min i.v.) on continued ANP infusion resulted in marked further enhancement of natriuresis, independent of changes in glomerular filtration rate (GFR). In the second set of experiments, in which oncotic pressure in the postglomerular capillaries was elevated by hyperoncotic exchange transfusion, administration of ANP did not result in natriuresis, even though GFR increased by the same magnitude as that seen in isoncotic animals given ANP. These observations are consistent with the view that peritubular capillary hydraulic and oncotic pressures modulate the natriuretic and diuretic effects of ANP.