Diffusion-limited gas exchange across amphibian skin.

Cutaneous gas exchange function of amphibians is conveniently analyzed in lungless salamanders in which all gas exchange is through the skin. Measurements in Desmognathus fuscus (Plethodontidae) have yielded the following results: 1) Cutaneous transfer of O2 and CO2 is limited predominantly by diffusion. 2) Accordingly, in environmental hypoxia, O2 uptake decreases. 3) Anaerobiosis contributes to energy balance during the first few hours of hypoxia only. Thereafter unknown biochemical adjustments take place that allow the animal to restore metabolite levels characteristic of normoxia regardless of the continued reduced oxygen uptake.