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ENERGETICS OF AMINO ACID TRANSPORT INTO BRAIN SLICES: EFFECTS OF K + DEPLETION AND Rb + OR Cs + SUBSTITUTION ON AMINO ACID UPTAKE
Author(s) -
BanaySchwartz Miriam,
Teller D. N.,
Horn Babette,
Lajtha A.
Publication year - 1977
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.1471-4159.1977.tb10687.x
Subject(s) - ouabain , valinomycin , amino acid , chemistry , hepes , membrane transport , sucrose , ion , stereochemistry , ion transporter , metabolism , biochemistry , sodium , membrane potential , membrane , organic chemistry
— Mouse brain slices were depleted of K + by three 10‐min incubations‐in oxygenated HEPES‐buffered medium lacking glucose and K + . Addition of K + or Rb + (or Cs + , to a smaller degree) with glucose, or with succinate, malate, and pyruvate (SMP) before incubation at 37°C with 14 C‐amino acids restored active low‐affinity transport of d ‐Glu, α‐aminoisobutyrate (AIB), GABA, Gly, His, Val, Leu, Lys, and Orn. Ouabain at 1–2μ m with Rb + was more inhibitory with SMP than with glucose, suggesting that the glycoside may affect specific energy coupling to transport. Valinomycin, in contrast, showed no specificity of inhibition of amino acid uptake with glucose or SMP and K + or Rb + . Cs + partially restored amino acid uptake, but Li + was less effective than Cs + . NaF at 10 m m with SMP + Rb + , or SMP + K + did not inhibit amino acid uptake. Therefore, it was possible to dissociate glycolysis and Na + , K + ‐ATPase activity from amino acid transport. The ion replacements for K + that supported active amino acid transport indicate that the specificity of ions in possible ionic gradients for transport energetics should be reexamined.