Examination of the extraction methods and re-evaluation of blue fluorescence generated in rat tissues in situ.

Extraction methods for measuring blue fluorescence generated in rat liver and brain in situ were examined. Great care should be taken when the traditional chloroform/methanol extraction method is employed because artificial blue fluorescence is readily produced by subsequent light irradiation, or by passage through a silicic acid column. In contrast, sodium dodecylsulfate (SDS) extraction were found to be suitable since no artificial blue fluorescence was produced by subsequent light irradiation. The levels of blue fluorescence in rat tissues were re-evaluated following SDS extraction. The levels of blue fluorescence in rat liver increased with age, whereas those in rat brain did not. Accumulation of blue fluorescence in the tissues was only slightly enhanced by vitamin E-deficiency. Blue fluorescence in the extracts did not seem to be derived from autofluorescent yellow lipofuscin in situ. The results were not always consistent with earlier observations obtained using the chloroform/methanol extraction.