Gas exchange in isolated perfused frog skin as a function of perfusion rate.

Patches of skin were removed from bullfrogs and perfused with a red cell suspension through the cutaneous artery to define the gas exchange characteristics of frog skin without complications caused by in vivo regulatory mechanisms. Oxygen uptake was primarily perfusion limited at low perfusion rates but primarily diffusion limited at perfusion rates that were similar to cutaneous blood flows previously reported in vivo. Diffusing capacity (DO2) increased only slightly as perfusion rate increased. Because the DO2 in isolated skin, in which DO2 should be maximal, was not significantly higher than estimates of DO2 in vivo, there seems to be little opportunity for increasing cutaneous DO2 or oxygen uptake in vivo.