Stoll M S, Zenone E A, Ostrow J D
J Clin Invest. 1981 Jul;68(1):134-41. doi: 10.1172/jci110229.
Radiolabeled photobilirubins, prepared in vitro by anaerobic illumination of [34C]bilirubin, were injected intravenously into homozygous jaundiced Gunn rats with an external bile fistula. With the animals kept in darkness, the labeled photobilirubins were excreted rapidly in bile. Photobilirubins IA and IB were excreted primarily as unconjugated bilirubin, whereas photobilirubin II was excreted primarily as photobilirubin II and not converted into bilirubin. Bile of Gunn rats given no exogenous pigments, but undergoing phototherapy, contained a large proportion of photobilirubin II and, if collected in liquid nitrogen, traces of photobilirubins I; neither was found in bile when these rats were kept in the dark. Because there is prior evidence that these rats were kept in the dark. Because there is prior evidence that these photobilirubins are isomers of bilirubin, these experiments indicate that the major mechanism of phototherapy is photoisomerization of bilirubin. Photobilirubin II is the unidentified major photoderivative described previously, whereas formation of photobilirubins IA and IB, and their reversion to bilirubin-IXalpha, account for the remarkably increased output of the parent pigment during phototherapy.
通过对[34C]胆红素进行厌氧光照在体外制备的放射性标记光胆红素，被静脉注射到患有纯合性黄疸的带有外胆管瘘的冈恩大鼠体内。在动物处于黑暗环境下时，标记的光胆红素迅速经胆汁排泄。光胆红素IA和IB主要以未结合胆红素的形式排泄，而光胆红素II主要以光胆红素II的形式排泄，且未转化为胆红素。未给予外源性色素但接受光疗的冈恩大鼠的胆汁中含有很大比例的光胆红素II，若在液氮中收集，还含有微量的光胆红素I；当这些大鼠处于黑暗环境时，胆汁中未发现这两种物质。由于之前有证据表明这些大鼠处于黑暗环境。由于之前有证据表明这些光胆红素是胆红素的异构体，这些实验表明光疗的主要机制是胆红素的光异构化。光胆红素II是先前描述的未明确的主要光衍生物，而光胆红素IA和IB的形成以及它们向胆红素-IXα的逆转，解释了光疗期间母体色素输出显著增加的原因。
