Action of Aldosterone on the Bladder and Skin of the Toad

Abstract

ALDOSTERONE stimulates the active transport of sodium across the isolated urinary bladder and ventral skin of the toad (Bufo marinus), after treatment of the animal with the hormone and incubation of these membranes in its presence^1–3. With the toad bladder an interval of 1 h approximately elapses at room temperature between addition of aldosterone to the incubation fluid and the first noticeable increase in sodium transport, regardless of the concentration of the steroid. Yet, the amounts of aldosterone fixed on the bladder tissue exceeded medium concentrations after 15 min incubation². It was, therefore, proposed that aldosterone exerts its influence on the process under study via the stimulation of synthesis of a substance involved in the active transport of sodium¹. In view of the growing body of information pointing at a close relationship between protein synthesis and hormonal steroid action^4,5 it was thought that aldosterone might exert its action on this metabolic pathway. Investigations were, therefore, made with antibiotics characterized by their inhibiting properties on definite steps of protein synthesis. ‘Puromycin’ is at present considered as blocking ribosomal elaboration of proteins⁶, while actinomycin D presumably acts in the cell nucleus on the DNA-dependent synthesis of RNA^7,8.