Diffusion of oxygen through the mouse ear

Oxygen tension differences across the mouse ear have been measured polarographically under conditions of no blood flow. For some experiments the ear was split into two by cleavage along the central cartilage plate, and the diffusion of oxygen measured in both directions across these asymmetrical preparations. Measurements were also made on ears from which the stratum corneum had been removed by stripping with Sellotape. It was possible to relate these results to a simple multi-layer diffusion model. The main barrier to diffusion of oxygen resides in the stratum corneum, whose permeability is estimated to be 1 . 2 X 10(-8) ml O2 atm-1 cm-1 S-1. The permeability of the rest of the ear is 4 . 7 X 10(-7) ml O2 atm-1 cm-1 S-1. The inhibition of tissue respiration by the local injection of solutions of sodium amytal, potassium cyanide and other substances reduced the oxygen gradients by factors of between 3 and 7. Cooling the ear from room temperature to 0 degree C reduced the gradients by a factor of about 4.