Abstract
The effects of prostaglandin A2 (PGA2) on urine flow, glomerular filtration rate, mean arterial blood pressure, hematocrit, and net transtubular movements of water and urea in different parts of the nephron were evaluated using free flow recollection micropuncture technique in anesthetized nondiuretic rats. PGA2 was infused into the abdominal aorta above the renal arteries at a rate of 100 ng/min/kg b.wt. Urine flow increased 48% above control values and mean arterial blood pressure declined slightly while glomerular filtration rate remained relatively unaltered under PGA2 action. Inulin urine/plasma concentration ratio decreased from 364 ± 20 to 227 ± 17 and urea urine/plasma concentration ratio from 102 ± 8 to 80 ± 5, indicating that the fractional excretion of both water and urea was significantly increased. Mean late proximal inulin tubular fluid/plasma concentration ratio was markedly reduced (from 2.39 ± 0.11 to 1.85 ± 0.10 with P < .001) and the percentage of the filtrate that remained in late proximal convoluted tubules increased from 43.1 ± 2.0 to 55.7 ± 2.8 (P < .001) during PGA2 infusion, revealing a significant inhibitory action of this compound on proximal tubular reabsorption of sodium and water. A concomitant increase in reabsorption by the loop of Henle and to some extent the distal nephron largely compensated for proximal inhibition. Fractional urea reabsorption in the proximal tubules was not affected by PGA2 but urea recirculation from collecting duct to loop of Henle was reduced slightly. These observations are consistent with a possible role for prostaglandins in the intranenal regulaion of sodium and water reabsorption.
Footnotes
- Received March 26, 1973.
- Accepted July 13, 1973.
- © 1973 by The Williams & Wilkins Co.
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