IMPROVED STABILITY OF THE HUMAN EPIDERMAL MEMBRANE DURING SUCCESSIVE PERMEABILITY EXPERIMENTS

In many cases it is instructive to use a single human epidermal membrane (HEM) sample to perform successive in vitro permeability experiments under varied experimental conditions. This study focused upon the feasibility of such successive permeability experiments in side-by-side, two-chamber diffusion cells. It was shown that for permeability experimental protocols which involved performing one permeability experiment per day and extensive washing between permeability experiments, the barrier properties of HEM samples were altered significantly within the first 72 h of the protocol. However, if the HEM is supported in the diffusion cell with a porous synthetic membrane, a single HEM sample remains essentially unaltered with respect to mannitol permeability and electrical resistance for up to 5 days. This suggests that protecting the HEM from physical stress is an essential element in performing successive permeability experiments.