Iontophoretic permselectivity of mammalian skin: characterization of hairless 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 vitro research.

METHODS

Na+ transport numbers were determined by the Hittorf method or by the measurement of membrane potential. The skin isoelectric point was deduced from the electroosmosis of mannitol (a polar non-electrolyte) as a function of pH.

RESULTS

The Na+ transport number across porcine skin, like that for hairless mouse, indicated a modest cation permselectivity. Consistent with this observation, the isoelectric 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 physiological pH, both of these model membranes supports a net negative charge.

CONCLUSIONS

The permselective properties of porcine and hairless mouse skin are similar (but with the porcine membrane having apparently fewer basic or more weakly-acidic groups than that of the mouse) and consistent with the characteristics, which have been deduced elsewhere, of human skin.