Effects of restriction of sodium or administration of fludrocortisone on parotid salivary kallikrein in man.

Urinary kallikrein is increased by restriction of dietary sodium and by administration of fludrocortisone, a sodium-retaining steroid. In order to determine whether salivary kallikrein responds similarly, we studied 16 normal volunteers after 1-week periods of daily intake of 9, 109, and 259 mEQ of sodium; 10 subjects were studied after addition of 0.6 mg/day fludrocortisone for a week to a regimen of 109 mEq/day sodium. During sodium restriction, parotid saliva had a significantly higher mean concentration of kallikrein ad potassium and a significantly lower concentration of sodium than during periods of intake of 109 or 259 mEq/day sodium. Sodium restriction also caused significantly higher urinary excretion of kallikrein and aldosterone. Salivary amylase remained unchanged during the three sodium periods. Administration of fludrocortisone significantly increased the mean concentration of parotid kallikrein and excretion of urinary kallikrein in comparison with control levels, however the concentrations of parotid sodium and potassium did not change significantly. Four patients studied before and after removal of aldosterone-producing adenomas each showed decreased concentrations of parotid kallikrein and potassium and increased concentrations of parotid sodium after surgery. It is concluded that both salivary and urinary kallikrein increased in response to restriction of sodium and that these increases were mediated by levels of sodium-retaining steroid. Increased output of kallikrein in response to increased levels of sodium-retaining steroid may be a generalized response of organs that contain glandular kallikrein and can conserve sodium.