GABA receptors on horizontal cells in the goldfish retina.
We investigated the localization of GABA(A) and GABA(C) receptors in horizontal cells (HCs) and HC axon terminals (ATs) dissociated from goldfish retina, using whole-cell patch-clamping recordings. Applications of GABA on HCs induced two groups with inward currents at the holding potential of -50 mV: One was a sustained inward current in the H1 cell, with one type of HCAT (AT1), and the other was a transient inward current in other HC soma and HCAT (AT2). Co-application of GABA with bicuculline or SR95531, GABA(A) receptor antagonists, showed a non-blocking effect in the sustained current, but a blocking effect in the transient current. The sustained current was evoked by cis-4-aminocrotonic acid (CACA), a GABA(C) receptor agonist, while the transient current was not induced by CACA, but mimicked by muscimol, a GABA(A) receptor agonist. Both the sustained and transient currents were completely blocked by picrotoxin and not mimicked by baclofen, a GABA(B) receptor agonist. Thus H1 cell and AT1 have GABA(C) receptors, while H2, H3 cells and AT2 have GABA(A) receptors.
Paik
Sun-Sook
SS
Physics and Biophysics Section, Department of Natural Sciences, College of Medicine, The Catholic University of Korea, 505 Banpo-dong Socho-gu, 137-701, Seoul, South Korea.
Park
No Gi
NG
Lee
Sung-Jong
SJ
Han
Hye-Kyong
HK
Jung
Chang-Sub
CS
Bai
Sun-Ho
SH
Chun
Myung-Hoon
MH
D000818:Animals; D004594:Electrophysiology; D018755:GABA Agonists / Q000494:pharmacology; D018756:GABA Antagonists / Q000494:pharmacology; D006054:Goldfish; D018408:Patch-Clamp Techniques; D018079:Receptors, GABA / Q000502:physiology*; D012160:Retina / Q000166:cytology* / Q000502:physiology
D018755:GABA Agonists; D018756:GABA Antagonists; D018079:Receptors, GABA