A. Arnarsson et T. Eysteinsson, Modification of the Xenopus electroretinogram by actions of glycine in theproximal retina, ACT PHYSL S, 169(3), 2000, pp. 249-258
The electroretinogram (ERG) was recorded from the Xenopus retina, to examin
e the effects of glycine and strychnine on these responses and to determine
the origins of these changes. Glycine at concentrations between 0.1 and 10
mM reduced the b- and d-waves of the ERG in a dose-dependent manner, while
strychnine increased their amplitude. 2-Amino-4-phosphonobutyric acid (APB
) reduced the b-wave and blocked the effect of glycine, but not strychnine,
on the d-wave. When the d-wave had first been blocked by kynurenic acid (K
YN) or reduced by (+/-)cis-2,3-piperidine dicarboxylic acid (PDA) the b-wav
e was enhanced by glycine, but not by strychnine. N-methyl-DL-aspartate (NM
DLA), which alters responses in the proximal retina only, blocked the effec
ts of glycine and strychnine on the ERG. This suggests that the glycinergic
effects on the ERG are at least partly mediated by processes in the proxim
al retina. The results further support the suggestion that inhibitory neuro
transmitters in the proximal retina may modulate both the b- and d-waves of
the Xenopus ERG.