The Contributions of Diffusion and Flow to the Passage of D₂O through Living Membranes.: Effect of Neurohypophysenl Hormone 011 Isolated Anuran Skin.

Abstract

Summary. 1. Equations are derived, describing the contributions of diffusion and flow to the passage of isotopic water through membranes of different structure. 2. For pore membranes the permeability as measured by osmotic flow is always larger than the permeability as calculated from the diffusion of isotopic water. 3. Neurohypophyseal extracts increase the net flow of water through the isolated toad skin (with 1/10 Ringer on the outside and Ringer on the inside) by 100 to 200 %. The diffusion rate of heavy water through the skin is, on the other hand only slightly increased. 4. The results are consistent with the assumption that neurohypophyseal hormone increases the pore size in some layer of the skin without increasing the total area available to diffusion. Active transport of water may, however, contribute to the water transfer.