Failure to demonstrate a hormonal inhibitor of proximal sodium reabsorption

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Abstract

Recently, it has been reported that a humoral inhibitor of proximal sodium reabsorption could be detected in plasma, and dialysates of plasma, of rats and dogs undergoing saline diuresis. We have repeated these studies using similar techniques and protocols. Fractional sodium reabsorption by the proximal tubule (as estimated in free-flow micropuncture studies from tubule fluid-to-plasma inulin ratios) was found not to be lower during infusion of “natriuretic” plasma than during subsequent infusion of “hydropenic” plasma. Similarly, infusion of natriuretic plasma failed to prolong reabsorptive half-time of the shrinking drop beyond that seen during hydropenic plasma infusion. No increase in urine volume or rate of sodium excretion was observed during the period of natriuretic plasma infusion, nor did natriuretic plasma result in an increase in these measures in rats undergoing water diuresis.

Authors

Fred S. Wright, Barry M. Brenner, Cleaves M. Bennett, Robert I. Keimowitz, Robert W. Berliner, Robert W. Schrier, Pierre J. Verroust, Hugh E. De Wardener, Heinz Holzgreve