Excretion of Human Urinary Kinins

Kinins in relation to kallikrein activity, kininogen, electrolytes, aldosterone and catecholamines in urine from normal individuals

The object of the present study was to test the hypothesis that urinary kinin excretion is an indicator of intrarenal kinin formation and to investigate urinary excretion of kinins in relation to natriuresis, kaliuresis, diuresis and urinary aldosterone and catecholamines in normal individuals on a free salt and water intake. In freshly voided urine collected from 24 normal individuals kinin concentration was directly related to kallikrein activity. Kininogen concentration was very low and neither related to kallikrein activity nor to kinin concentration. The excretion rates of kinins and kininogen were unrelated to the time interval between micturitions. In 24 hour urine collections from 50 normal individuals the excretion of kinins was positively correlated to natriuresis, kaliuresis and diuresis and also to dopamine but not to aldosterone, noradrenaline and adrenaline. Kinin excretion was inversely related to age and was lower in women than in men. On the basis of these results it is concluded that urinary kinin excretion reflects intrarenal kinin formation in normal ambulatory individuals and that urinary kinins are formed mainly in the interstitial and vascular space of the kidney. Furthermore, kinins and dopamine seem to play a physiological role in the renal handling of electrolytes and water.

Changes of urinary kallikrein and kinin excretions induced by adrenalin infusion in conscious dogs

A subpressor dose of adrenalin (0.5 mg/h) infused intravenously into nine conscious trained dogs increased urine kinin excretion from 41 +/- 9 ng/h to 191 +/- 29 ng/h. The effect was abolished by phenoxybenzamin pretreatment (1 mg/kg). In alpha-blocked condition adrenalin increased urine TAMe-esterase activity from 12.7 +/0 2.3 mEU/h to 15.7 +/- 2.8 mEU/h whilst in beta-blocked condition the catecholamine decreased urine enzyme activity from 12.7 +/- 1.0 mEU/h to 11.7 +/- 1.1 mEU/h. Adrenalin invariably decreased urine sodium excretion. In comparable experiments with dopamin (1.0 mg/h) a slight natriuresis was observed, yet urine kallikrein and urine kinin excretions remained unmodified.