Comparison of transcutaneous permeability in skins of larval and adult salamanders (Ambystoma tigrinum).

The electrical properties and transcutaneous movements of Na, Cl, and water were compared (in vitro) in skins of larval and adult forms of Ambystoma trigrinum. Larval skin had a mean transcutaneous potential difference of 6 mV (inside positive) in adults it was 50 mV. Short-circuit current (Isc) was, respectively, about 2 microA x cm-2 and 20 microA x cm-2. Electrical resistances were similar. Passive effluxes of Na and Cl were similar in both forms but Na influx (active direction) was much greater in the adult. Diffusional permeability to water was less in the larval salamander skin. Influx of Na and Isc were increased by vasotocin in the adult but not larval skin. Water permeability was unaffected by vasotocin in either form. The properties of the premetamorphic skin are compared to those of two other urodele amphibians.