The influence of thyroxine on the sodium, chloride, and water balance of the toad Bufo bufo

Abstract

Thyroxine injections have been shown to alter the cutaneous salt balance and urine composition of the starved adult toad Bufo bufo. The net losses of sodium and chloride into the tap water in which the toads were immersed became a net gain after 3 days of thyroxine. This gain was sustained with further daily injections of thyroxine. Urinary volume and total excretion of sodium and chloride were reduced after thyroxine treatment, thus the ion concentrations were decreased. The present in vivo results have been discussed in relation to in vitro effects of thyroxine previously observed on toad bladder and skin. The changes in electrolyte balance during natural moulting, which is controlled in part by thyroxine, are compared to those observed in the present experiments. Weight loss during the first 7 days of thyroxine administration suggests, under the present experimental conditions, a possible metabolic effect of the hormone.