Bradykinin B2 receptor antagonist increases chloride and water absorption in rat medullary collecting duct

• Published in: The American journal of physiology Vol. 271; no. 2 Pt 2; p. R352
• Main Authors: Mukai, H, Fitzgibbon, W R, Bozeman, G, Margolius, H S, Ploth, D W
• Format: Journal Article
• Language: English
• Published: United States 01.08.1996
• Subjects: Absorption; Animals; Blood Pressure - drug effects; Bradykinin - analogs & derivatives; Bradykinin - pharmacology; Bradykinin Receptor Antagonists; Chlorides - metabolism; Diuresis - drug effects; Drug Resistance; Female; Hemodynamics - drug effects; Kidney Medulla; Kidney Tubules, Collecting - metabolism; Rats; Rats, Inbred Strains; Renal Circulation - drug effects; Sodium Chloride - pharmacology; Water - metabolism
• ISSN: 0002-9513
• DOI: 10.1152/ajpregu.1996.271.2.r352

This study tested the hypothesis that intrarenal kinins play a regulatory role in electrolyte excretion by altering Cl- absorption in the collecting duct. We measured Cl- and insulin concentrations in tubular fluid samples obtained from medullary collecting ducts (MCD) of Dahl/Rapp salt-resistant (SR/ Jr) rats by microcatheterization of ducts of Bellini before and after treatment with the bradykinin receptor antagonist HOE-140. Tubular fluid was obtained from paired terminal inner medullary (t-IMCD) and outer medullary (OMCD) collecting duct sites of the left kidney. HOE-140 (n = 7) or vehicle (n = 5) was infused intravenously, and the collections were repeated. HOE-140 did not alter glomerular filtration rate but decreased urine flow rate (P < 0.05) and absolute and fractional Cl- excretion (P < 0.01). HOE-140 did not alter the fraction of filtered Cl- delivered (FDCl) to the OMCD but decreased FDCl to the t-IMCD from 2.3 +/- 0.3 to 1.3 +/- 0.3% (P < 0.05). The fraction of filtered Cl- absorbed per millimeter between the collection sites was increased from 0.2 +/- 0.1 to 0.6 +/- 0.1% (P < 0.05). Fractional absorption of water along the MCD was also increased (P < 0.05). No changes in excretory function or tubular Cl- or water absorption were observed in vehicle-treated rats. These studies show that kinin B2 receptor blockade enhances Cl- and water absorption in the MCD, a finding that supports a role of renal kinins in the regulation of NaCl and water excretion.