Kidney volume expansion and prostaglandin release by bradykinin. The effect of indomethacin pretreatment.

100 ng/kg/min bradykinin was infused into the left renal artery in anaesthetized dogs which were loaded with 10% mannitol in saline to produce a diuresis of approximately 1 ml/min. Bradykinin initially increased renal blood flow (70%), kidney volume (20%). Kidney volume, diuresis and urine osmolarity remained equally changed during continuous kinin infusion, while other parameters subsided toward the control levels. When renal blood flow was maintained constant during the infusion of bradykinin, urine PG-excretion increased (330%), the glomerular filtration decreased (60%) and this was accompanied by decreased kidney volume, diuresis/natriuresis with unchanged urine osmolarity. Indomethacin treatment (2.5 mg/kg i.v.) decreased renal blood flow (35%) and inhibited urine PG-excretion. Bradykinin after indomethacin showed effects which were very similar to those observed before indomethacin treatment. It is concluded that increased intratubular volume is a main determinant of bradykinin induced increase of whole kidney volume. The accompanying increase of intrarenal pressure does not apparently contribute to the kinin induced PG-release. The vasodilation by bradykinin seems independent of released prostaglandins. The diuresis/natriuresis and decreased urine osmolarity are probably of hemodynamic origin.