Figure 5.

Influence of acute barrier disruption or exogenous sphingomyelinase on ceramide and sphingomyelin content. Barrier disruption and isolation of the epidermis (2 and 4 hours after treatment) were performed as described in Figure 1. Epidermal homogenates were incubated with exogenous sphingomyelinase for 2 hours. Lipids were extracted by the method of Bligh and Dyer (30), separated by HPTLC, shown for ceramides in (a) and analyzed by laser densitometry after charring of the HPTLC plates (b).