Net taurine transport and its inhibition by a taurine antagonist

Lena Lewin, David K. Rassin, Åke Sellström

Research output: Contribution to journalArticle

3 Scopus citations

Abstract

P2-fractions were isolated from rat brain, and used to study net taurine transport. The fractions were incubated in increasing concentrations of [3H]taurine and the intraterminal concentration measured by liquid scintillation and amino acid analysis. The membrane potential of the isolated fractions was estimated using86Rb+ as a marker for intracellular K+. Taurine was synthesized in the P2-fraction when incubated in taurine free medium. At external taurine concentrations below 370 μM a significant amount of the endogenous taurine was released to the incubation medium. Net taurine uptake into the P2-fraction was achieved at external taurine concentrations exceeding 370 μM. The taurine antagonist 6-aminomethyl-3-methyl-4H, 1, 2, 4-benzothiadiazine-1, 1-dioxide (TAG) competitively inhibited taurine and [3H]taurine transport into the P2-fraction. As the external concentration of taurine was increased, the accumulation of86Rb+ into the P2-fraction was facilitated. This indicated an increasing hyperpolarization of the neuronal membrane as taurine transport shifted from release towards uptake. TAG reduced the hyperpolarization that paralleled taurine accumulation, in a dose dependent manner. Our results indicate that relatively low transmembranal gradients of taurine may be maintained by an electrogenic taurine transporter having a large transport capacity. Such a transporter may well serve the needs of osmotic regulation, i.e. to transport large amounts of taurine in any direction across the neuronal membrane.

Original languageEnglish (US)
Pages (from-to)347-352
Number of pages6
JournalNeurochemical Research
Volume19
Issue number3
DOIs
StatePublished - Mar 1 1994

Keywords

  • Taurine transport
  • ion gradients
  • membrane potential
  • nerve terminals
  • osmo-regulator
  • taurine antagonist

ASJC Scopus subject areas

  • Biochemistry
  • Cellular and Molecular Neuroscience

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