Role of Skin and Neurohypophyseal Hormones in the Adaptation of the Toad Bufo viridis to High Salinities

Abstract

MANY people maintain that ADH is important in the control of water and salt metabolism of amphibia¹. The toad Bufo viridis is one of the species most resistant to dehydration and high ambient salinity, in which situations it has a high plasma salt concentration. In toads adapted to high salinity, the urine sodium chloride concentration increases to about plasma level, whereas active sodium transport, as measured by short circuit current, is almost completely reduced (ref. 2 and our measurements). The animals apparently do not drink and water is passively transferred along the osmotic gradient from the ambient solution into the body. We found that the sensitivity to added hormone was lost from the skins of animals that were adapted to saline solutions above 400 mosm.