Role of volume depletion in the glycerol model of acute renal failure

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Abstract
Previous studies have demonstrated significant volume depletion early in the course of glycerol-induced acute renal failure. In addition, it has been shown that acute volume expansion within 6 h of glycerol administration reverses the fall in inulin clearance but volume expansion 12-24 h after glycerol fails to restore that parameter to normal. The current studies were performed to determine whether chronic volume expansion would prevent the fall in inulin clearance normally observed 18-20 h after the insult. Inulin clearance was therefore compared 18-20 h after glycerol in hydropenic rats and in rats undergoing chronic volume expansion by the constant infusion of Ringer solution at a rate of 5 ml/h initiated at the time of the glycerol injection. Inulin clearance was well maintained in the latter group, averaging 1.77 compared with 0.22 ml/min in the hydropenic group. Renal histology revealed no difference in the degree of tubular necrosis between groups but did show a marked decrease in cast formation in the animals undergoing chronic volume expansion. To determine the possible significance of these casts, micropuncture studies were carried out to measure proximal tubular pressures. Under hydropenic conditions these pressures were not different control animals and rats receiving glycerol when studied 18-20 h after glycerol. Following acute volume expansion, however, glycerol-treated rats demonstrated significantly higher pressures than control rats. On the other hand, proximal tubular pressures were comparable in glycerol-treated and control animals receiving the chronic volume expansion.(ABSTRACT TRUNCATED AT 250 WORDS)