Cutaneous osmoregulation in Triturus cristatus carnifex (Laur.) (Urodela)

Abstract

In the crested newt ( Triturus cristatus carnifex Laur.), osmotic permeability and active sodium transport (the latter studied by the short-circuit current technique) in the isolated skin change cyclically during the year. The lowest values for both parameters are recorded in winter (aquatic phase), while the highest values are recorded in summer (terrestrial phase). Prolactin (24 IU of ovine prolactin subdivided into three injections delivered on alternate days) administered during the terrestrial phase (coincident with the low rate of hormone release) induces a drastic drop in both osmotic permeability and active sodium uptake. Conversely, hypophysectomy performed during the aquatic phase increases both the osmotic permeability and active transport of sodium across the skin. The role played by the skin in the osmoregulatory mechanism of the crested newt is discussed.