Effect of Phototherapy on Hepatic Microsomal Drug Metabolism in Heterozygous and Homozygous Gunn Rats

Phototherapy for the treatment and prevention of neonatal infant jaundice is widely practiced. The effectiveness of photo-therapy in reducing hyperbilirubinemia in jaundiced infants is very well established,1’2 however, its widespread use has raised some doubts and concerns about its safety.3 Although, the short-term effects of phototherapy for the most part are minimal4, fluorescent light has been shown to be both toxic5 and mutagenic6 to mammalian cells. It has been demonstrated that visible light (450nm) is able to induce genetic changes in prokaryotic as well as eukaryotic cells7 and that the illumination of isolated DNA in the presence of bilirubin and/or riboflavin8–9 resulted in alterations in the physical and biochemical properties of this biopolymer. Gantt et a1 1 0 reported that cool-white fluorescent light exposure resulted in both DNA damage and chromatid breaks in mouse cells. Futhermore, Speck and Rosenkranz11 reported structural changes in the DNA isolated from human cells grown in culture after exposure to high intensity illumination in the absence of added photosensitizers.