Induction of bradykinin B-1 hypotensive receptors in rats by lipopolysaccharide

Bolus injections of bradykinin (BK, 0.25-1.0 nmol . kg(-1) intraarterially (i.a.)) in anesthetized rats produced a dose-dependent hypotensive response, while desArg(9)-BK (0.25-1.0 nmol . kg(-1) i.a.), Lys-desArg(9)-BK (0.25-1.0 nmol . kg(-1) i.a.), and Sar[D-Phe(8)]desArg(9)-BK (0.5-1.0 nmol . kg(-1) i.a.) were inactive. At 12-24 h after the pretreatment with lipopolysaccharide (10-100 mu g . kg(-1) i.v.), BK produced a greater decrease in blood pressure than in nontreated rats and Sar[D-Phe(8)]desArg(9)-BK (0.5-1.0 nmol . kg(-1) i.a.) decreased blood pressure by 13.0+/-1.0 and 22.2+/-2.31 mmHg (1 mmHg = 133.3 Pa), whereas both desArg(9)-BK and desArg(10)-kallidin were inactive. The hypotensive effect of BK (0.25-1.0 nmol . kg(-1) i.a.) was significantly reduced by HOE-140 (1.0 nmol . kg(-1) i.a.) given 5 min before and that of Sar[D-Phe(8)]desArg(9)-BK was reduced by [Leu(8)]desArg(9)-BK (1.0 nmol . kg(-1) i.a.) given 3 min before the agonists. These results indicate that in rats lipopolysaccharide induces B-1 receptors in 18 to 24 h. B-1 agonists protected from degradation are needed to demonstrate the presence of B-1-receptor-mediated hypotension in the rat.