Blockade of renal medullary bradykinin B^sub 2^ 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... (BKB...) receptors to acutely increase papillary blood flow (PBF) and therefore ... excretion. We determined the effect of acute inner medullary interstitial (IMI) BKB... 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 ...g*kg...*h..., 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 ... excretion (urinary ... extraction rate) and fractional ... 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... receptors to increase ... excretion independent of changes in inner medullary blood flow. (ProQuest: ... denotes formulae/symbols omitted.)