pH influences the postpulse permeability state of skin after electroporation

The pH dependence of porcine epidermis permeability and the influence of pH on the electroporation transport of molecules were studied. The resistance was maximum at pH 5 and decreased with an increase or decrease in the pH of the donor medium. The permeability coefficient of glucose was significantly higher at pH 7.5, compared to pH 5. On electroporation, the resistance recovery rate of porcine epidermis was rapid below pH 5 and slower at above pH 7.5. The transport studies revealed that a donor medium pH above 7.5 helps to maintain the postpulse permeability state of the skin. By changing the donor medium pH from 5 to 7.5, the postpulse transport of glucose and fluorescein isothiocyanate (FITC)-labeled dextran (MW 10 kDa) (FD10K) was enhanced by about threefold. The lipids extracted from porcine epidermis showed pI values of 4.3 and 5.9. Vesicles of these lipids fused more rapidly at pH 5 than at pH 3, 7, and 10. The results imply that pH-sensitive postpulse resistance recovery and molecular transport are due to the charge states of epidermal lipids.