Physiological Mechanisms Regulating Rate of Urinary Flow in Renal Disease.

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Abstract
Studies were made on 4 healthy male control subjects and on 7 patients suffering from renal disease: 4 from chronic glomerulonephritis, 1 from acute glomerulonephritis, 1 from chronic pyelonephritis, and 1 from polyceptic kidneys with severe renal insufficiency. 24-hr.- samples of urine were collected from all subjects who were permitted fluids ad lib, and measurements made of freezing-point depressions and concns. of Na, chloride, K, urea, and creatinine chromogen in urine and serum. A linear relationship was observed between the urinary osmotic load (mOsm/min.) and the rate of urinary flow (ml/min.) in 7 patients suffering from renal disease. This suggests that osmotic diuresis is the major physiological mechanism regulating the rate of urinary flow in these patients. In these patients there appears to be a "critical" level of the glomerular filtration rate, approx. 10 ml./min., at which: a) Ck/CCr. exceeds 100%; b) V/Ccr exceeds 15%; c the antidiuretic response to single intraven. injns. of Pitressin in physiological dosage (0.57 mU/Kg.) is markedly diminished; d) there is an alteration in the relationship between V/CCr and the urinary concns. of Na, K and total solute.