Age-dependent renal responses to the bradykinin B-2-receptor antagonist icatibant in conscious lambs

To investigate the role of endogenously produced bradykinin in modulating r enal function during postnatal maturation, various parameters of glomerular and tubular function were measured for 1 h before and after intravenous in jection of 12.5 mug/kg of the specific B-2-receptor antagonist icatibant to conscious, chronically instrumented lambs aged similar to1 (n = 7) and sim ilar to6 wk (n = 7). In response to icatibant, and in the absence of any ch anges in renal hemodynamics, there was an similar to 80% decrease in glomer ular filtration rate (GFR) at 20 min in 1-wk-old lambs that was sustained f or 60 min; in 6-wk-old lambs, there was an similar to 70% decrease in GFR b y 20 min, with control levels being reached by 40 min. Icatibant administra tion was also associated with significant decreases in urinary flow, Cl-, a nd K+ excretion rates that were similar in both groups of lambs, whereas Na + excretion decreased only in 6-wk-old lambs. We conclude that bradykinin m odulates glomerular and tubular function in an age-dependent manner.