PHOTOSENSITIZING EFFECTS OF 8‐METHOXYPSORALEN ON THE SKIN OF HAIRLESS MICE—I. FORMATION OF INTERSTRAND CROSS‐LINKS IN EPIDERMAL DNA

Abstract

Abstract— The photomediated induction of interstrand cross‐links by 8‐methoxypsoralen has been measured in the epidermal DNA of hairless mice. Equivalent efficiencies for cross‐link induction were determined for HRS/J/Anl and SKH: hairless‐1 mice. A wavelength dependence on the relative efficiency of cross‐link induction was observed; a broad spectrum light source, 300–400 nm, was approximately 5 times more effective in cross‐link formation than a 365 nm light source. Repeated exposure to 8‐methoxypsoralen followed by ultraviolet light, 5 times a week for 6 weeks, altered epidermal thickness and resulted in a decreased efficiency for DNA cross‐link formation.