A differential effect of APB on ON- and OFF-center ganglion cells in the dark adapted rabbit retina.
The glutamate analog, 2-amino-4-phosphonobutyric acid (APB) is a proven tool in exploring the retinal circuit; it has been shown to interfere specifically with the transmission from photoreceptor to depolarizing bipolar cell. Consequently, in photopic retinae, the application of APB disrupts the ON-channel leaving the OFF-channel undisturbed; on the other hand, in the scotopic state, APB application blocks all ganglion cell responses. In this paper, we will show that the ON- and OFF-channels have a differential sensitivity to application of APB. That is to say, APB blocks center responses in ON-ganglion cells at mean concentration of 22 +/- 5.1 microM (mean +/- standard error of the mean; n = 15) and in OFF-ganglion cells at mean concentration of 91 +/- 15.5 microM (n = 16). Since considerable data rule out direct effects of APB on ganglion cells, we hypothesize that this effect is due to a difference in the synaptic gain of ON and OFF pathways in the inner retina.
Jin
X T
XT
Department of Biology, Boston College, Chestnut Hill, MA 02167, USA.
Brunken
W J
WJ
D000064:Acclimatization; D000613:Aminobutyrates / Q000494:pharmacology*; D000818:Animals; D003624:Darkness; D004305:Dose-Response Relationship, Drug; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology*; D066298:In Vitro Techniques; D010775:Photic Stimulation; D011817:Rabbits; D012044:Regression Analysis; D012160:Retina / Q000033:anatomy & histology / Q000502:physiology*; D012165:Retinal Ganglion Cells / Q000166:cytology / Q000187:drug effects / Q000502:physiology*
D000613:Aminobutyrates; D018690:Excitatory Amino Acid Agonists; C012729:2-amino-4-phosphonobutyric acid