IMPROVED STABILITY OF THE HUMAN EPIDERMAL MEMBRANE DURING SUCCESSIVE PERMEABILITY EXPERIMENTS

In many cases it is instructive to use a single human epidermal membra ne (HEM) sample to perform successive in vitro permeability experiment s under varied experimental conditions. This study focused upon the fe asibility of such successive permeability experiments in side-by-side, two-chamber diffusion cells. It was shown that for permeability exper imental protocols which involved performing one permeability experimen t per day and extensive washing between permeability experiments, the barrier properties of HEM samples were altered significantly within th e 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 r emains 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 su ccessive permeability experiments.