EFFECT OF ALDOSTERONE IN VITRO ON ACTIVE SODIUM TRANSPORT AND MOULTING OF FROG SKIN

It is shown that aldosterone in concentrations higher than 1.5 · 10–9 M induces a moult in vitro, and that the moult is accompanied by characteristic changes in the potential and the short‐circuit current. The sequence of changes can be divided into four parts: the first constant period, the inhibition period, the spontaneous activation period and the second constant period. At a concentration of 7 · 10–7 M aldosterone the inhibtion starts 2–4 hrs and the activation 4–7 hrs after the addition. Furthermore it has been shown that the short‐circuit current is higher in the second constant period as compared to the control skin half. During the spontaneous activation period the net sodium flux exceeds the short‐circuit current by 25 %. The changes in chloride flux and sodium efflux during the moulting cycle were rather small. Both the moult and the activation of the short‐circuit current were abolished by actinomycin D. A hypothesis which could explain the behavior during the moulting cycle and the activation of the sodium transport is given. © 1969 Scandinavian Physiological Society