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Cation Dependence of Hypotaurine Uptake in Mouse Brain Slices
Author(s) -
Kontro P.,
Oja S. S.
Publication year - 1981
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1981.tb00455.x
Subject(s) - hypotaurine , neuroscience , chemistry , neurochemistry , biology , taurine , biophysics , neurology , biochemistry , amino acid
Mouse brain slices take up hypotaurine (2‐aminoethanesulphinic acid) from medium by means of two concentrative low‐ and high‐affinity transport systems. [ 35 S]Hypotaurine uptake by the slices was significantly reduced in the absence of external potassium, calcium, or magnesium ions. An excess of potassium ions also inhibited hypotaurine uptake by one‐half. Uptake was almost completely abolished on removal of sodium ions. The K m constants for both low‐ and high‐affinity transport components increased in a low‐sodium medium, suggesting that sodium ions are required when hypotaurine is attached to its possible carrier sites in plasma membranes. Sodium ions also mimicked allosteric effectors of hypotaurine transport, showing positive cooperativity. More than two sodium ions may be involved in the transport of one hypotaurine molecule across the cell membrane. The calculated activation energies of transport were fairly similar in normal and sodium‐deficient media and thus sodium ions may not participate in the activation mechanisms of the transport. With respect to cation dependence, hypotaurine transport in brain slices exhibits features characteristic of neurotransmitter amino acids.