Cellular aspects of phototoxic reactions induced by kynurenic acid. I. Establishment of an experimental model utilizing in vitro cultivated cells.

Kynurenic acid is an endogenously occurring tryptophan metabolite, which, under certain conditions, may accumulate in human tissues. In earlier work kynurenic acid showed a pronounced photohemolytic capacity, and conclusive evidence has been presented that the reaction is mediated by singlet oxygen. The aim of the present study was to gain further information about the cellular mechanisms involved in the photo-oxidative damage induced by kynurenic acid. This paper is mainly concerned with the establishment of a proper experimental model utilizing in vitro cultivated cells, but basal cytotoxic effects revealed by the use of cell growth curves, and light- and scanning electron microscopic examinations are also described.