“WATER DIURESIS” PRODUCED DURING RECUMBENCY BY THE INTRAVENOUS INFUSION OF ISOTONIC SALINE SOLUTION 1

Abstract

Inhibition of the antidiuretic activity of the supra-optico-hypophyseal system has been previously recognized to occur as the result of hypo-tonicity of the extracellular fluid, hypnotic suggestion, alcohol administration, exposure to cold, and direct trauma to the hypothalamus or pituitary. The effect of rapid isotonic expansion of the volume of extracellular fluid by intraven. administration of 3 liters of 0.9% NaCl soln. was studied in 6 expts. carried out on 3 essentially healthy men. With the subjects recumbent, there was in each expt., a sharp rise in urine flow, a fall in the urinary concn. of Na and Cl to below their respective concns. in extracellular fluid as well as in the infusion soln., together with a marked decrease in urine specific gravity, urine, urea concn., and creatinine U/P ratio. During or following the infusion urine flows increased from control values of approx. 2ml./min. to as much as 9 ml./min., urine specific gravity fell from 1.010 or higher to 1.002, and creatinine U/P ratios fell from control values of 60 or more to as low as 12. This "water diuresis" continued for 1-2 hrs. That the distribution as well as the magnitude of the expanded extracellular fluid volume is important may be inferred from the failure of the subjects to manifest a similar response when they received an identical infusion while sitting. When the recumbent posture was subsequently assumed a similar water diuresis soon followed.