Steroid induced changes of the renal kallikrein-kinin system in rats

In male Sprague-Dawley rats the influence of salt loading (1% NaCl), deoxycorticosterone acetate (2 X 15 mg/kg/day resp. 250 mg/kg sc), corticosterone (2 X 20 mg/kg/day sc) and adrenocorticosterone (0.5 mg/kg/day tetracosactid sc) on the activity of renal kallikrein and renal renin activity was investigated. Salt loading lowered renal kallikrein activity, deoxycorticosterone stimulated its activity and in combination they had no effect on renal kallikrein activity. The time course of kallikrein stimulation by deoxycorticosterone showed no relationship to the escape phenomenon of the kidney from the sodium retaining effect of the mineralocorticoid hormone. Reduction of endogenous mineralocorticoid hormones by adrenalectomy caused a marked reduction of urinary and renal kallikrein activity. Corticosterone suppressed the activity of the renal kallikrein-kinin system at the same time as the reduction in urinary aldosterone excretion. Adrenocorticotrophin caused the same decrease in the activity of renal kallikrein as corticosterone. Urinary aldosterone excretion, however, was significantly stimulated. Thus, the known positive correlation between kallikrein and aldosterone was missing. In all experiments the urinary excretion of kallikrein correlated highly with the kallikrein activity measured in renal cortical tissue. However, no correlation was found between kallikrein and urine volume or urinary excretion of sodium and potassium. In our experiments no relationship between the activity of the renin-angiotensin system and that of the renal kallikrein-kinin system was observed. Furthermore, no clear relationship was found between systemic blood pressure and the activity of the renal kallikrein-kinin system.