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 decreas e 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 numb er 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 structur e, which is interpreted as involving different transport behavior viz, aque ous pathways which are either predominantly perpendicular or parallel to th e SC. Our observations are consistent with the hypothesis that localized aq ueous pathway formation (electroporation) occurs first, followed by seconda ry processes involving the entry of water into the SC and also localized he ating. (C) 1998 Elsevier Science S.A. AU rights reserved.