Long-lasting changes in GABA responsiveness in cultured neurons.
In neuronal cells, GABA evokes an increase in chloride conductance by activating GABA(A) and GABA(C) receptors. In mature neurons, this increase in conductance generally has a hyperpolarizing and inhibitory action. Using gramicidin-based perforated patch recordings, we show that in cultured motor neurons GABA-induced currents are significantly altered following activation of GABA receptors coinciding with changes in membrane potential. Changes in intracellular chloride concentration constituted the mechanism for this modulation. Because of low resting chloride conductance and low activity of chloride transporters, changes in intracellular chloride concentration and hence GABA response were long-lasting (time constant of recovery was about 2.5 min). Cultured dorsal horn and hippocampal neurons exhibited a similar response pattern, suggesting a general property of cultured neuronal cells. These long-lasting changes in GABA responsiveness may have major implications on neuronal excitability.
Chabwine
Joelle N
JN
Laboratory of Physiology, Geert Callewaert, KULeuven, Campus Gasthuisberg, Herestraat 49, B-3000 Leuven, Belgium.
Van Damme
Philip
P
Eggermont
Jan
J
De Smedt
Humbert
H
Missiaen
Ludwig
L
Van Den Bosch
Ludo
L
Parys
Jan B
JB
Robberecht
Wim
W
Callewaert
Geert
G
D000818:Animals; D002478:Cells, Cultured; D002712:Chlorides / Q000378:metabolism; D006624:Hippocampus / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects; D009046:Motor Neurons / Q000378:metabolism*; D009433:Neural Inhibition / Q000502:physiology; D018408:Patch-Clamp Techniques; D020671:Posterior Horn Cells / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D005680:gamma-Aminobutyric Acid / Q000378:metabolism* / Q000494:pharmacology
D002712:Chlorides; D005680:gamma-Aminobutyric Acid