The effects of aldosterone and spironolactone on renal kallikrein in the rat.

1. A technique has been developed for the measurement of kallikrein 'production' in rat renal cortical cells in suspension. 2. After preparative steps, column chromatography on DEAE-cellulose yielded a peak of alpha-N-tosyl-L-arginine methyl ester (Tos-Arg-OMe) esterase activity identical with kallikrein isolated from rat urine in respect of pH optimum, effects of inhibitors, biological activity and immunological properties. 3. The nutrient medium surrounding incubated cells contained measurable kallikrein activity, which was increased by aldosterone and decreased by spironolactone. 4. The results raised the possibility that kallikrein could be an aldosterone-induced protein.