Taurine in the Retina

Abstract

Since the original observations of Kubícěk and Dolének (1958), many people have confirmed the predominance of taurine in retinal tissue from a range of species. There is, however, considerable variation in the concentrations reported, with, for example, the values for rat retina ranging between 10 and 90 μmol/g wet wt. Although the differences may relate to techniques, the association of high or low values with a particular method is not obvious, as amino acid analyzers have yielded values (recalculated) of 10–40 μmol/g wet wt. (e.g., Pasantes-Morales et al., 1972; Macaione et al., 1974), whereas results from dansylation range between 14 and 90 μmol/g wet wt. (e.g., Yates and Keen, 1975; Lund Karlsen and Fonnum, 1976). Using double-label dansylation (Snodgrass and Iverson 1973), we routinely find a value of about 50 μmol/g wet wt. for this tissue (Table 13.1) and have been concerned that we might be including a contaminant in our measurements: The derivatives of cysteine, cystine, hypotaurine, cysteamine, cystathionine, and cysteic acid can be distinguished. Separation of dansylated compounds is achieved by chromatography on thin-layer micropolyamide plates, and, at a tissue dilution commensurate with the estimation of other free amino acids in retinal extracts, dansyl taurine is usually seen as a large, highly fluorescent spot.