ACTIVE SODIUM UPTAKE BY THE TOAD AND ITS RESPONSE TO THE ANTIDIURETIC HORMONE

Abstract

Anesthetized male and female toads of the sp. Bufo bufo were placed in a frog Ringer bath containing radioactive Na24. The Ringer solution was shown to be isotonic with the toad''s extracellular fluid. Insipidin, an extract of the posterior pituitary containing 20 I.U. of the vasopressor substance/ml, was injected subcutaneously in experimental animals, and an inactivated preparation of the same material was given to controls. Each injection was 0.1 ml. Water uptake from the bath was measured simultaneously with uptake of Na24 before and after giving the active or inactive preparations. The uptake of Na24 was determined by placing the whole animal into a specially constructed steel chamber beneath an end-window Geiger-Muller tube. Water uptake was determined by weight changes. There was a marked increase in the amount of Na24 taken up by the toads receiving the active preparation. Both experimental and control animals took up water during the experiments. It was concluded that the posterior pituitary preparation used had a definite positive effect on the rate of active Na transport through the skin of the whole animal and that this effect was at least partially independent of the rate of water transfer.