Journal of Neurophysiology, Vol 64, Issue 1 57-63, Copyright © 1990 by APS
GABAA-receptor-activated current in dorsal root ganglion neurons freshly isolated from adult rats
G. White
Section of Electrophysiology, National Institute of Alcohol Abuse and Alcoholism, Rockville, Maryland 20852.
1. gamma-Aminobutyric acid (GABA) is the major inhibitory neurotransmitter
affecting dorsal root ganglion (DRG) neurons. This study compares
properties of current activated by the GABAA receptor in two populations of
DRG neurons. DRG neurons were isolated from adult rat with the use of
enzymatic and mechanical means. Within hours of being isolated, neurons
were recorded from with the use of the whole-cell variant of the
patch-clamp technique. 2. One population of neurons exhibited an
afterdepolarizing potential (ADP), a low threshold for action-potential
generation (-45 to -50 mV), a short-duration action potential (less than 2
ms) that was abolished in the presence of 1-2 microM tetrodotoxin (TTX),
and an insensitivity to 50 nM capsaicin. The second population of neurons
exhibited a high threshold for action-potential generation (less than -40
mV), a shoulder on the falling phase of the action potential, insensitivity
of action-potential generation to TTX (1-2 microM), and a depolarizing
response to application of 50 nM capsaicin. 3. Sensitivity to GABA (over
the range of 1-1,000 microM) was comparable for the two populations of
neurons. 4. GABA-activated current was greater in ADP neurons than in
non-ADP-type neurons of a comparable diameter (30-50 microns). The mean +/-
SE amplitude of current activated by 10 microM GABA in ADP neurons was
0.310 +/- 0.050 nA (range = 0.110-0.460 nA, n = 8), and 0.037 +/- 0.016 nA
(range = 0.010-0.130 pA, n = 7) in non-ADP neurons. Ten microM GABA
elicited cell firing in ADP neurons but not in non-ADP neurons.(ABSTRACT
TRUNCATED AT 250 WORDS)
