Hypotaurine uptake by brain slices from adult and 8-day-old mice

Uptake of [35S]hypotaurine by brain slices prepared from adult and 8-day-old mice was studied at varying temperatures, under O2 and N2 atmospheres, and in the presence of metabolic inhibitors and varying concentrations of hypotaurine in the incubation medium. The tissue/medium concentration gradients generated were exceptionally high for an amino acid. Hypotaurine uptake was energy- and temperature-dependent, more strictly in adult mice. Uptake was saturable, containing a high-affinity and a low-affinity component. The estimated transport constants for the high-affinity uptake of hypotaurine (8-day-old mice, 17.2 mumol/liter; adults, 35.3 mumol/liter) were of the same order of magnitude as the reported transport constants of putative amino acid transmitters, but the total transport capacity appears to be greatest for hypotaurine.