Taurine transport and metabolism in human retinoblastoma cells

These findings suggest that the Y79 retinoblastoma cell may be a useful experimental system in which to study certain aspects of taurine metabolism. The cells contain high concentrations of taurine when they are grown under normal conditions. This can occur in two ways. One is through synthesis of taurine from serine; the other is by taurine uptake facilitated by a high-affinity transport system. These results regarding synthesis and uptake are consistent with what has been reported for retinal preparations from other species (Lombardini 1980; Sabceda 1980; Schmidt 1980; Pourcho 1981; Adler 1983). The retinoblastoma cells did not release taurine, however, when they were depolarized. Cultured chick embryo retinal neurons also do not release taurine following depolarization (Adler 1983). Therefore, neither of these culture systems provides any evidence for a direct role of taurine release in retinal neurotransmission. The retinoblastoma cells take up relatively low concentrations of taurine more efficiently through the high-affinity transport system when they are enriched in docosahexaenoic acid (22:6). This suggested the possibility that the high 22:6 content of the retina may be related specifically to taurine utilization. Additional studies revealed, however, that the transport effect was not specific for either 22:6 or taurine. Enrichment with arachidonic acid, an n-6 polyunsaturate that cannot be converted to 22:6, produced a similar enhancement of taurine uptake (Yorek et al. 1984).(ABSTRACT TRUNCATED AT 250 WORDS)