Bradykinin B2 receptor antagonist increases chloride and water absorption in rat medullary collecting duct.
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.
Mukai
H
H
Department of Medicine, Medical University of South Carolina, Charleston 29425, USA.
Fitzgibbon
W R
WR
Bozeman
G
G
Margolius
H S
HS
Ploth
D W
DW
D000042:Absorption; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001920:Bradykinin / Q000031:analogs & derivatives* / Q000494:pharmacology; D065168:Bradykinin Receptor Antagonists; D002712:Chlorides / Q000378:metabolism*; D004231:Diuresis / Q000187:drug effects; D004351:Drug Resistance; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D007679:Kidney Medulla; D007685:Kidney Tubules, Collecting / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012079:Renal Circulation / Q000187:drug effects; D012965:Sodium Chloride / Q000494:pharmacology; D014867:Water / Q000378:metabolism*
D065168:Bradykinin Receptor Antagonists; D002712:Chlorides; D014867:Water; D012965:Sodium Chloride; C065679:icatibant; D001920:Bradykinin