Ca2+-mediated suppression of the GABA-response through modulation of chloride channel gating in frog sensory neurones.
A suppressant effect of intracellular free Ca2+ on the gamma-aminobutyric acid (GABA)-induced chloride inward current (ICI(GABA)) was studied in isolated frog sensory neurones under whole cell voltage clamp. Voltage-dependent Ca2+ influx elicited during the steady state of ICI(GABA)-induced a fast, slowly recovering current relaxation in the outward direction, the amplitude of which was dependent on total Ca2+ influx. This suppressant effect showed specificity for different divalent cations, suggesting action at a specific intracellular effector. Single channel recording revealed a Ca2+-dependent decrease in the duration of the open time of the GABA-gated Cl- channel without change in single channel conductance.
Behrends
J C
JC
Department of Physiology, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
Maruyama
T
T
Tokutomi
N
N
Akaike
N
N
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002712:Chlorides / Q000378:metabolism / Q000502:physiology*; D005727:Ganglia, Spinal / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D007473:Ion Channels / Q000378:metabolism / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects; D009475:Neurons, Afferent / Q000187:drug effects / Q000502:physiology*; D011892:Rana catesbeiana; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology*
D002712:Chlorides; D007473:Ion Channels; D005680:gamma-Aminobutyric Acid; D002118:Calcium