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OR Ziv, RJ Jensen, JF Rizzo; In Vitro Activation Of Ganglion Cells In Rabbit Retina: Effects Of Glutamate Receptor Agents . Invest. Ophthalmol. Vis. Sci. 2002;43(13):4474.
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Purpose: Determine whether the long-latency responses of ganglion cells to electrical stimulation are due to activation of cells deep within the retina. Methods: Action potentials of individual ganglion cell axons were recorded extracellularly in superfused adult New Zealand White rabbit retinas in a dimly lit room. Ganglion cells were stimulated electrically by the inner wire (125 um diameter) of a concentric bipolar electrode, positioned on the inner retinal surface over the center of the receptive field of a ganglion cell. The electrical stimulus was a 2 msec current pulse. The return electrode was an Ag/AgCl surface located underneath the sclera (transretinal stimulation). Drugs were applied through the bath. Results: Ganglion cells responded to electrical stimulation with a short-latency (3-5 msec) action potential, followed by a burst of action potentials (n=4-8) that occurred 11-50 msec following current onset. To understand the source of these delayed action potentials, we examined the effects of glutamate receptor agents. Both (20-40 µM) NBQX and CNQX, which are AMPA/kainate receptor antagonists, abolished the responses OFF-center cells while sparing the short latency spike that was attributable to direct stimulation of the ganglion cell. AP4 (120-170 µM), an mGluR6 receptor agonist known to block transmission from photoreceptors to ON-bipolar cells, abolished the responses in ON-center ganglion cells but not OFF-center ganglion cells. Conclusion: Our results indicate that the long-latency burst of action potentials are due to activation of presynaptic cells rather than direct stimulation of ganglion cells.
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