Local transport regions LTRs in human stratum corneum due to long and short ‘high voltage’ pulses

Ž . Ž . Application of ‘high voltage’ HV pulses transdermal voltage U )50 V to preparations of human skin have been previously skin Ž . hypothesized to cause electroporation of multilamellar lipid barriers within the stratum corneum SC . Such pulses cause large increases Ž . in molecular transport and decrease in the skin’s electrical resistance. Here we describe the local transport regions LTRs and the Ž . surrounding local dissipiation regions LDRs that dominate the skin’s response to both ‘long’ and ‘short’ HV pulses. The number of LTRrLDRs depends on U , but their size depends on pulse duration, so that LDRs can merge to form large regions containing several skin 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 Ž . 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. q 1998 Elsevier Science S.A. All rights reserved.