Effect of urinary alkalinization on the intrarenal formation of kinins

Alterations in the urinary excretion rate of kallikrein (UKKV) have frequently been assumed to reflect alterations in the intrarenal generation of kinins. Since other factors such as urinary pH and the activity of renal kininases may affect the intrarenal concentration of kinins, we investigated the effect of urinary alkalinization on kinin excretion in the presence and absence of kininase II inhibition. Urine was collected from the ureters of rats during control (ctl) (0.15 M NaCl infusion) and experimental (exp) periods. During exp periods, group I (time control) was infused with 0.15 M NaCl, group II with 0.3 M NaCl, and groups III and IV with 0.3 M NaHCO3, all at 0.12 ml/min. Prior to the ctl period, group IV was pretreated with the kininase II inhibitor captopril (40 mg/kg). During the exp period, urinary kinin excretion (UKiV) increased significantly in all groups ([exp - ctl] UKiV = 21 +/- 7, 27 +/- 9, 52 +/- 14, and 70 +/- 9 pg X min-1 X kg-1 in groups I, II, III, and IV, respectively). Urinary pH increased significantly in groups II, III, and IV. The increases in UKiV and pH were significantly greater in the bicarbonate-infused rats than in control. Partial correlation coefficients show that UKiV correlates with a high degree of significance only with urinary pH (r = 0.6). During the ctl period, UKiV in the captopril-pretreated rats was not different from that in other groups.(ABSTRACT TRUNCATED AT 250 WORDS)