GABAA membrane currents are insensitive to extracellular acidification in cultured sensory neurons of the frog.
The effects of decreasing extracellular pH from 7.4 to 6.0 or 5.8 on whole cell membrane currents induced by GABA (10-100 microM) were studied in dorsal root ganglion (DRG) neurons of the frog in short-term culture using the whole cell patch-clamp technique. In 45 of 50 cells the GABA currents were the same at both normal and reduced pH. In the remaining 5 cells, acidification increased the response. The reversal potential for the current, about +5 mV, was the same at reduced and normal pH. These results contrast with the effect of the same pH reduction which markedly reduces the current resulting from glutamate activation of receptors on central neurons (Traynelis and Cull-Candy 1990, Vyklický Jr. et al. 1990, Tang et al. 1990). These findings suggest that acidification under pathophysiological conditions plays a protective role in preventing excessive excitation not only by decreasing glutamate responses but also by leaving the inhibitory GABAA responses intact.
Vyklický
L
L
Institute of Physiology, Academy of Sciences of the Czech Republic, Prague.
Philippi
M
M
Kuffler
D P
DP
Orkand
R K
RK
D000143:Acids / Q000378:metabolism*; D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D004594:Electrophysiology; D005110:Extracellular Space / Q000378:metabolism*; D005727:Ganglia, Spinal / Q000166:cytology; D006863:Hydrogen-Ion Concentration; D009475:Neurons, Afferent / Q000187:drug effects* / Q000502:physiology*; D011894:Rana pipiens; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology*
D000143:Acids; D005680:gamma-Aminobutyric Acid