Selective effects of enzyme treatment used for dissociating single cells on their GABA-receptor activities.
Frog dorsal root ganglion (DRG) cells treated with collagenase and trypsin were dissociated mechanically. The characteristics of dose-response curves of GABA-induced Cl- currents (ICl) were mainly studied using the "concentration-clamp" technique, by which the external solution around isolated single neurons was rapidly changed within a few milliseconds. The saturating maximum currents induced by various concentrations of GABA normalized to the peak ICl induced by 10(-5) M GABA on the same neuron varied from 1.5 to 5.5 among the neurons, though the absolute maximum currents varied little. The Hill coefficients (n = 1.92 +/- 0.09, mean +/- S.D.) also varied little on the neurons. The time constants of the desensitization phase of fully activated GABA responses were not so markedly different among the neurons. The present results suggested a possibility that the enzyme treatment produced a selective inactivation of alpha 1 unit, a high affinity subtype of the GABA-receptor.
Inoue
M
M
Department of Physiology, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
Akaike
N
N
D000818:Animals; D005727:Ganglia, Spinal / Q000187:drug effects / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects; D003012:Microbial Collagenase / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D011892:Rana catesbeiana; D011963:Receptors, GABA-A / Q000502:physiology*; D014357:Trypsin / Q000494:pharmacology*; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology*
D011963:Receptors, GABA-A; D005680:gamma-Aminobutyric Acid; D014357:Trypsin; D003012:Microbial Collagenase