Effect of kinin receptor antagonists on renal hemodynamic and natriuretic responses to volume expansion
Fenoy, F.J.; Roman, R.J.
American Journal of Physiology 263(5 Pt 2): R1136-R1140
1992
ISSN/ISBN: 0002-9513 PMID: 1332518 Document Number: 394030
The role of kinins in the natriuretic and papillary blood flow (PBF) responses to intravenous administration of 0.9% sodium chloride solution equal to 5% of body weight over 30 min was evaluated using a B-1-kinin receptor antagonist (des-Arg-9, (Leu-8)bradykinin, 2.5 mu-g/min iv) and a B-2-kinin receptor antagonist (D-Arg,(Hyp-3,Thi-5,8,D-Phe-7)bradykinin, 2.5 mu-g/min iv). In control rats, PBF increased 43 +- 5% after the volume expansion with saline. Administration of the B-1-kinin receptor antagonist had no significant effect on basal PBF or the rise in PBF produced by volume expansion. In contrast, administration of the B-2-kinin receptor antagonist decreased basal PBF by 18 +- 3% and prevented the rise in PBF during volume expansion. Urine osmolality was lower in the rats treated with the B-1-antagonist and higher in rats infused with the B-2-kinin antagonist than in control animals after volume expansion (587 +- 47 and 1,082 +- 83 vs. 907 +- 124 mosmol/kgH-2O, respectively). The initial natriuretic response during the first 30 min after volume expansion was similar in rats given vehicle or the kinin antagonists. However, cumulative sodium excretion over the 2-h course of the experiment was significantly lower in the rats given the B-2-receptor antagonist than in control rats (92 +- 7 vs. 101 +- 9% of the administered load). The B-1-kinin receptor antagonist had no effect on cumulative sodium excretion; however, glomerular filtration rate was 30% lower in rats receiving the B-1-antagonist than in control rats after volume expansion. These results indicate that the rise in PBF after intravenous infusion of saline can be blocked by a B-2-kinin receptor antagonist and that this modifies to a minor extent the pattern of sodium excretion after administration of a sodium load.