抄録
It has been demonstrated that Cortisol increases sodium reabsorption in the proximal tubule, the ascending limb of the loop of Henle and the distal tubule. To make more quantitative analysis, studies were performed in Wister strain rats using the modified technique of “distal blockade ”. By sequentially administering triamterene, chlorothiazide and ethacrynic acid during Mannitol infusion with replacement of urinary losses, increments in sodium excretion were used to calculate sodium reabsorption in the proximal tubule (TNa prox), in the ascending limb of the loop of Henle (TNa Henle), at both of the proximal site (TNa D1) and the distal site (TNa D2) of the distal tubule. On the control experiments, TNa prox was 41.3±7.7 (Mean±SE) μEq/min; TNa Henle, 18.0+6.6 μEq min; TNa D1, 40. 0±6. 9 μEq/min; TNa D2, 16.3±4.3 μEq/min. On the Cortisol administered group, TNa prox increased to 58.9±3.2 sEq/min (p<0.05), TNa Henle increased to 37.8±6.6 pEq /min (p<0.05), TNa D1 remained at 43.2±6.6 pEq/min and TN5D2 increased to 35.1+3.4 μEq/min (p<0.005). In addition, it was shown that there were no alterations in fractional sodium reabsorption rates (% of FNa) at fhese sites of the nephron. It has been concluded, therefore, that Cortisol enhances sodium reabsorption along all parts of the nephron except D1 almost uniformly.
