A patch-clamp study of GABA- and strychnine-sensitive glycine-activated currents in post-natal tissue-cultured hippocampal neurons.
GABA- and strychnine-sensitive glycine-activated currents in post-natal tissue-cultured hippocampal neurons were studied by using patch-clamp techniques. Current-voltage relations for both agonists in symmetrical Cl- solutions showed outward rectification. Strychnine-sensitive glycine-activated currents have not been studied in detail before in post-natal tissue-cultured hippocampal neurons. Partial desensitization of whole-cell currents was observed in symmetrical Cl- solutions during bath application of GABA- and glycine. In F-/Cl- solutions, both agonists gave a PF/Pcl value of about 0.06. The reversal potentials in mixtures of Cl- and SO4(2-) solutions were close to the equilibrium potentials of Cl- in the presence of both GABA and glycine. Single channels in inside-out excised patches with 2 mumol l-1 GABA and 5 mumol l-1 glycine in the pipette showed outward current rectification. The dose-response curves for GABA and glycine gave Kd values of 52 and 61 mumol l-1, respectively, and Hill coefficients close to 2. GABA and glycine binding were competitively blocked by their respective antagonists (bicuculline and strychnine). The similarities between GABA- and glycine-activated currents and the response in a combination of saturating concentrations of both GABA and glycine implied that the two agonists activated comparable numbers of anatomically distinct channels with very similar permeation properties.
D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D018118:Chloride Channels; D002712:Chlorides / Q000378:metabolism / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D005998:Glycine / Q000494:pharmacology*; D006624:Hippocampus / Q000502:physiology*; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D008433:Mathematics; D008565:Membrane Proteins / Q000187:drug effects / Q000502:physiology*; D008962:Models, Theoretical; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D013331:Strychnine / Q000494:pharmacology*; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology*
D018118:Chloride Channels; D002712:Chlorides; D007473:Ion Channels; D008565:Membrane Proteins; D005680:gamma-Aminobutyric Acid; D013331:Strychnine; D005998:Glycine