Local transport regions (LTRs) in human stratum corneum due to long and short 'high voltage' pulses

Application of 'high voltage' (HV) pulses (transdermal voltage U-skin > 50 V) to preparations of human skin have been previously hypothesized to cause electroporation of multilamellar lipid barriers within the stratum corneum (SC). Such pulses cause large increases in molecular transport and decrease in the skin's electrical resistance. Here we describe the local transport regions (LTRs) and the surrounding local dissipiation regions (LDRs) that dominate the skin's response to both 'long' and 'short' HV pulses. The number of LTR/LDRs depends on U-skin, but their size depends on pulse duration, so that LDRs can merge to form large regions containing several LTRs. LTRs themselves are not spatially homogeneous, as they have a ringlike structure, which is interpreted as involving different transport behavior viz, aqueous pathways which are either predominantly perpendicular or parallel to the SC. Our observations are consistent with the hypothesis that localized aqueous pathway formation (electroporation) occurs first, followed by secondary processes involving the entry of water into the SC and also localized heating. (C) 1998 Elsevier Science S.A. AU rights reserved.