Sodium Conservation in Normal and Hypophysectomized Dogs

Abstract

Two of 5 normal dogs on a restricted Na intake of 1 meq. daily for 45-50 days showed no change in the plasma Na level, while 3 showed a slight fall. In 3 runs on 3 hypophysectomized dogs large decreases occurred at or before 3 weeks, and significant falls occurred in the other 3 runs at 4 to 5 weeks. The amts. of Na lost during depletion periods were estimated from the amts. retained on replenishment. In general these were much larger than the negative balances observed during the depletion periods, and are considered a better measure of Na loss. The reason for the apparently erroneously low negative balances is not known. If the values for the negative Na balances during depletion are correct, the improbable conclusion follows that on depletion Na is sequestered in some inaccessible site and remains there permanently. The amts. of Na lost/kg./day on depletion are greater in hypophysectomized than in normal dogs.