MACROMOLECULE TRANSPORT IN AND EFFECTIVE PORE-SIZE OF ETHANOL PRETREATED HUMAN EPIDERMAL MEMBRANE

This study has examined the transport behavior of macromolecules of up to about 18 000 molecular weight (Mol. Wt) and the feasibility of usi ng the theory of restricted diffusion of molecules through cylindrical pores to predict/characterize the pore sizes of synthetic membranes a nd ethanol pretreated human epidermal membrane (HEM). To minimize memb rane and skin variabilities, experiments were conducted consecutively with each membrane using a two-chamber diffusion cell. Reference perme ants or electrical resistance measurements were used to monitor possib le membrane changes during a given set of runs. All HEM specimens exhi bited the same pattern of significantly decreasing permeability with i ncreasing polystyrene sulfonate (PSS) molecular weight. Previously obt ained permeability data for ethanol pretreated HEM with polypeptides ( leuprolide, CCK-8 and insulin) were found to be consistent with those for PSS; comparable permeability coefficients were observed for polype ptides and PSS's of comparable sizes. An analysis based on the theory of restricted diffusion for PSS transport across a synthetic Nuclepore (R) membrane yielded results consistent with the nominal pore size (ap proximately 75 angstrom) of this membrane. A similar analysis of the P SS data obtained with ethanol pretreated HEM yielded estimates of effe ctive pore size for this membrane in the range, 22-54 angstrom.