Effect of pharmacologic doses of vasopressin on sodium reabsorption in the rat kidney.
Administration of pharmacologic doses of vasopressin (50 mU./min./kg.) to the rat resulted in significant increases in both the urinary excretion of sodium (0.02 +/- 0.02 to 6.24 +/- 0.76 micronEq/min.) and the urine flow rate (4.5 +/- 0.5 to 30.5 +/- 6.0 micronl/min). Simultaneous free-flow micropuncture studies demonstrated a decrease in end-proximal TF/Pinulin ratios from 2.82 +/- 0.15 to 1.90 +/- 0.90 (p less than 0.01), indicating decreased water reabsorption in this portion of the nephron. To reduce the influence of the pressor effect of these doses of vasopressin on the kidney, the aorta was constricted proximal to the renal arteries and this resulted in a decrease in urinary sodium excretion to 2.87 +/- 0.57 micronEq/min. and in urine flow rates to 16.6 +/- 3.6 micronl/min. compared with animals given vasopressin alone. End-proximal TF/Pinulin ratio was 2.01 +/- 0.15, a value not significantly different than that in animals given vasopressin alone, suggesting a continued proximal inhibitory effect of vasopressin. It is concluded that pharmacologic doses of vasopressin inhibit sodium reabsorption in the proximal convoluted tubule as well as in distal portions of the nephron. The magnitude of sodium excretion observed is a function both of vasopressin inhibition of sodium reabsorption and the pressor effect of vasopressin.
D000818:Animals; D001794:Blood Pressure; D004285:Dogs; D005919:Glomerular Filtration Rate; D006400:Hematocrit; D007668:Kidney / Q000502:physiology*; D007677:Kidney Function Tests; D012964:Sodium / Q000378:metabolism*; D014667:Vasopressins / Q000494:pharmacology*
D014667:Vasopressins; D012964:Sodium