Blockade of renal medullary bradykinin B2 receptors increases tubular sodium reabsorption in rats fed a normal-salt diet.
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.
Sivritas
Sema-Hayriye
SH
Department of Medicine, Division of Nephrology, Medical University of South Carolina, 96 Jonathan Lucas Street, Charleston, SC 29425, USA.
Ploth
David W
DW
Fitzgibbon
Wayne R
WR
D000818:Animals; D001920:Bradykinin / Q000031:analogs & derivatives / Q000494:pharmacology; D065094:Bradykinin B2 Receptor Antagonists; D004039:Diet, Sodium-Restricted; D007679:Kidney Medulla / Q000098:blood supply / Q000187:drug effects / Q000378:metabolism*; D007705:Kinins / Q000378:metabolism*; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D043782:Receptor, Bradykinin B2 / Q000378:metabolism*; D012079:Renal Circulation; D012964:Sodium / Q000378:metabolism*; D017673:Sodium Chloride, Dietary / Q000008:administration & dosage
D065094:Bradykinin B2 Receptor Antagonists; D007705:Kinins; D043782:Receptor, Bradykinin B2; D017673:Sodium Chloride, Dietary; C065679:icatibant; D012964:Sodium; D001920:Bradykinin; D019331:NG-Nitroarginine Methyl Ester