IONTOPHORETIC PERMSELECTIVITY OF MAMMALIAN SKIN - CHARACTERIZATION OFHAIRLESS MOUSE AND PORCINE MEMBRANE MODELS

Purpose. To evaluate the transport number of Na+, and the isoelectric point, of two skin membranes frequently used for iontophoretic in vitr o research. Methods, Na+ transport numbers were determined by the Hitt orf method or by the measurement of membrane potential. The skin isoel ectric point was deduced from the electroosmosis of mannitol (a polar non-electrolyte) as a function of pH. Results. The Na+ transport numbe r across porcine skin, like that for hairless mouse, indicated a modes t cation permselectivity. Consistent with this observation, the isoele ctric points of porcine and hairless mouse skin were determined to be in the ranges of 3.5-3.75 and 4.5-4.6, respectively, That is, at physi ological pH, both of these model membranes supports a net negative cha rge, Conclusions, The permselective properties of porcine and hairless mouse skin are similar (but with the porcine membrane having apparent ly fewer basic or more weakly-acidic groups than that of the mouse) an d consistent with the characteristics, which have been deduced elsewhe re, of human skin.