title: Effect of preheating on the permeability of neonatal rat stratum corneum to alkanols.
abstract: We heated flat sheets of neonatal rat stratum corneum for various times at temperatures between 40 and 90 degrees C before determining the permeability coefficient (Kp) of propanol and/or hexanol from water. Below 70 degrees C, Kp remained constant; at 75 degrees C, Kp increased linearly with exposure time; at 80 degrees C and above, there was a large increase in under 2 h, with no further increase on longer heating. There was a 15-fold increase in 6-h Kp between 70 degrees C and 80 degrees C, values being constant above 80 degrees C but at a figure less than for lipid-extracted stratum corneum. Thermal analysis showed that the increase in Kp corresponds to changes in the 80 degrees C lipid endotherm, suggesting that the increased Kp is due to a disordering of the lipid structures. The effect of treating preheated stratum corneum with dimethylsulfoxide (DMSO) vapor for 16 h was also studied. Below 70 degrees C, Kp was increased five-fold, but between 70 and 80 degrees C this difference was eliminated, so that above 80 degrees C the Kp was the same as with heat treatment alone. We concluded that both heat and DMSO affect the lipid structures of stratum corneum. DMSO produced a small, reversible structural change, while the effect of heat is irreversible and produces a greater degree of disorder in the lipid structures, but the lipid still contributed to the barrier effect of stratum corneum.
authors: School of Pharmacy, Robert Gordon's Institute of Technology, Aberdeen, Scotland.
authors: S M
authors: SM
authors: Al-Saidan
authors: A J
authors: AJ
authors: Winfield
authors: A B
authors: AB
authors: Selkirk
mesh_terms: D000433:1-Propanol / Q000378:metabolism*; D000818:Animals; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D004817:Epidermis / Q000502:physiology*; D005740:Gases; D000441:Hexanols / Q000378:metabolism*; D006358:Hot Temperature; D066298:In Vitro Techniques; D008055:Lipids / Q000502:physiology; D010539:Permeability; D051381:Rats; D013997:Time Factors
chemical_list: D005740:Gases; D000441:Hexanols; D008055:Lipids; D000433:1-Propanol; D004121:Dimethyl Sulfoxide