THE EFFECT OF SODIUM INTAKE ON THE URINARY HISTAMINE IN ADRENALECTOMIZED RATS.

The daily excretion (mug/day) of free histamine has been measured in bilaterally adrenalectomized or sham-operated female rats. In rats developing adrenal insufficiency when kept on a "sodium free" diet, the output of free histamine in the urine fell progressively. The volume of urine was unchanged. In rats with adrenal insufficiency the oral administration of 0.9% saline caused an immediate rise in the urinary excretion of histamine. The rise was sustained for several days. Adrenalectomized rats consuming 43 mg/day of sodium chloride or less developed adrenal insufficiency and the daily output of urinary histamine fell progressively. A sodium chloride intake of 90 mg/day prevented this fall. Adrenalectomized rats kept on 0.9% saline showed no significant changes during the first 7 days after adrenalectomy. From the 8th day onwards the daily output of histamine in the urine rose progressively. After sham operation the daily output of histamine in the urine was not affected by the intake of sodium chloride. Adrenalectomized rats eat less food; a similar restriction of food intake in sham-operated rats decreased the urinary excretion of histamine. The decrease was, however, not as pronounced as in adrenalectomized rats developing adrenal insufficiency. Other sodium salts, but not glucose, had the same effect as 0.9% saline on the urinary excretion of histamine in adrenalectomized rats.