Tubular sodium handling in cold-exposed man during inhibition of distal tubular reabsorption of sodium

In 8 healthy volunteers in stable water diuresis, exposed to cold at +15 degrees C for 60 min, changes in excretion and tubular reabsorption of sodium and osmoles were studied by the clearance technique during inhibition of distal tubular sodium reabsorption following chlorothiazide infusion at 2 mg/kg/hr. Inhibition of distal tubular sodium reabsorption by chlorothiazide increased fractional sodium excretion to 6.5% and fractional excretion of osmoles to 7.5% of the filtered amount. The superimposed cold exposure did not further increase these figures, despite a significant cold-induced increase in arterial blood pressure.