Sivritas SH, Ploth DW, Fitzgibbon WR. Blockade of renal medullary bradykinin B2 receptors increases tubular sodium reabsorption in rats fed a normal-salt diet.
Am J Physiol Renal Physiol 2008;
295:F811-7. [PMID:
18632797 PMCID:
PMC2536883 DOI:
10.1152/ajprenal.90225.2008]
[Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2008] [Accepted: 07/11/2008] [Indexed: 11/22/2022] Open
Abstract
The present study was performed to test the hypothesis that under normal physiological conditions and/or during augmentation of kinin levels, intrarenal kinins act on medullary bradykinin B(2) (BKB(2)) receptors to acutely increase papillary blood flow (PBF) and therefore Na(+) excretion. We determined the effect of acute inner medullary interstitial (IMI) BKB(2) receptor blockade on renal hemodynamics and excretory function in rats fed either a normal (0.23%)- or a low (0.08%)-NaCl diet. For each NaCl diet, two groups of rats were studied. Baseline renal hemodynamic and excretory function were determined during IMI infusion of 0.9% NaCl into the left kidney. The infusion was then either changed to HOE-140 (100 microg.kg(-1).h(-1), treated group) or maintained with 0.9% NaCl (time control group), and the parameters were again determined. In rats fed a normal-salt diet, HOE-140 infusion decreased left kidney Na(+) excretion (urinary Na(+) extraction rate) and fractional Na(+) excretion by 40 +/- 5% and 40 +/- 4%, respectively (P < 0.01), but did not alter glomerular filtration rate, inner medullary blood flow (PBF), or cortical blood flow. In rats fed a low-salt diet, HOE-140 infusion did not alter renal regional hemodynamics or excretory function. We conclude that in rats fed a normal-salt diet, kinins act tonically via medullary BKB(2) receptors to increase Na(+) excretion independent of changes in inner medullary blood flow.
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