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Updated: Oct 2, 2026

GABA-activated Single-channel and Tonic Currents in Rat Brain Slices
Published on: July 17, 2011
Temperature effects on the presteady-state and transport-associated currents of GABA cotransporter rGAT1
Francesca Binda1, Elena Bossi, Stefano Giovannardi
1Laboratory of Cellular and Molecular Physiology, Department of Structural and Functional Biology, University of Insubria, Via Dunant 3, 21100, Varese, Italy.
Abstract:
The effects of temperature on the gamma-aminobutyric acid (GABA) uptake and on the presteady-state and transport-associated currents of the GABA cotransporter, rat gamma-aminobutyric acid transporter 1 (rGAT1), have been studied using heterologous oocyte expression and voltage-clamp. Increasing temperature from 15 to 30 degrees C increased GABA uptake, diminished the maximal value of the relaxation time constant of the presteady-state currents and increased the amplitude of the current associated with the transport of GABA. The curve of the presteady-state charge versus voltage was shifted toward negative potentials by increasing the temperature, while the maximal amount of charge (Q(max)) remained constant; the tau versus V curve was also negatively shifted by increasing temperatures. Analysis of the outward (alpha) and inward (beta) rate constants as functions of temperature showed that they are affected differently, with a Q(10)=3.4 for alpha and Q(10)=1.5 for beta. The different temperature coefficients of the rate constants account for the observed shifts. These observations are consistent with a charge moving mechanism based on a conformational change of the protein; the weaker temperature sensitivity of the inward rate constant suggests a rate-limiting diffusional component on this process.
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