Patch-clamp analysis of glycine-induced currents in chick ciliary ganglion neurons.
1. The whole-cell configuration of the patch-clamp technique was used to analyse currents induced by glycine in chick ciliary ganglion neurons freshly dissociated from 14- to 15-day-old embryos. 2. Application of glycine to cells voltage-clamped at -60 mV induced inward currents in all neurons tested. Dose-response curves yielded an EC50 of about 50 microM. Similar responses were elicited by beta-alanine and taurine though higher concentrations were required. 3. Strychnine reversibly inhibited the glycine-induced responses. The effect was dose dependent with a half-maximal effect being obtained with 20 nM strychnine. 4. Glycine-induced currents were inhibited by 100 microM Zn2+. The inhibition had slow rates of onset and recovery, in contrast to Zn2+ inhibition of GABA responses. Both bicuculline and d-tubocurarine inhibited glycine responses in a dose-dependent manner. 5. The steady-state I-V curve for glycine-induced currents was linear over the range -60 to +60 mV, but showed an outward rectification at very hyperpolarized membrane potentials. The reversal potential of glycine-induced currents shifted with changes in intracellular chloride concentration in a manner expected for chloride-selective channels. 6. Expression of functional glycine receptors during development was examined at embryonic day 8 (E8), 11, 14, and 18. The mean peak current was about 60-fold larger at E14 than at E8 and vastly exceeded changes in cell size. During the same period, responses to GABA increased only 2-fold in amplitude and correlated with changes in cell size.(ABSTRACT TRUNCATED AT 250 WORDS)
Zhang
Z W
ZW
Department of Biology, University of California, San Diego, La Jolla 92093-0357, USA.
Berg
D K
DK
D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D002642:Chick Embryo; D018118:Chloride Channels / Q000187:drug effects / Q000378:metabolism*; D002712:Chlorides / Q000378:metabolism*; D002924:Ciliary Body / Q000187:drug effects / Q000294:innervation* / Q000378:metabolism; D018756:GABA Antagonists / Q000494:pharmacology; D005726:Ganglia, Parasympathetic / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005998:Glycine / Q000494:pharmacology*; D018684:Glycine Agents / Q000494:pharmacology; D066298:In Vitro Techniques; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects; D018733:Nicotinic Antagonists / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D018009:Receptors, Glycine / Q000187:drug effects / Q000378:metabolism*; D013331:Strychnine / Q000494:pharmacology; D014403:Tubocurarine / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
D018118:Chloride Channels; D002712:Chlorides; D018756:GABA Antagonists; D018684:Glycine Agents; D018733:Nicotinic Antagonists; D018009:Receptors, Glycine; D005680:gamma-Aminobutyric Acid; D013331:Strychnine; D005998:Glycine; D014403:Tubocurarine; D001640:Bicuculline