On-bipolar cells and depolarising third-order neurons as the origin of the ERG-b-wave in the RCS rat.
In the retinas of Royal College of Surgeons (RCS) rats light induces an increase in distal extracellular potassium irrespective of the age, between days 19-24 and days 29-35 postpartum, but by days 29-35 the ERG b-wave has become reduced. The synaptic blocker 2-amino-4-phosphonobutyric acid (APB) causes the abolition of both the b-wave and the potassium increase at any age. MgCl2 greatly reduces the b-wave at all ages and abolishes the potassium increase in older rats, but in younger rats the potassium increase is enlarged. Since this increase occurs in the absence of the b-wave it is unlikely that the on-bipolar cells are the only sources of the b-wave. Because the NMDA receptor blocker ketamine reduces the b-wave, third order neurons, which possess NMDA receptors, could contribute to the b-wave.
Wurziger
K
K
Carl-Ludwig-Institute of Physiology, University of Leipzig, Liebigstr. 27, D-04103, Leipzig, Germany.
Lichtenberger
T
T
Hanitzsch
R
R
D000375:Aging / Q000502:physiology; D000818:Animals; D020148:Butyric Acid / Q000494:pharmacology; D016764:Cell Polarity / Q000502:physiology; D004596:Electroretinography / Q000187:drug effects; D005110:Extracellular Space / Q000187:drug effects / Q000502:physiology; D007649:Ketamine / Q000494:pharmacology; D015636:Magnesium Chloride / Q000494:pharmacology; D008954:Models, Biological; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000502:physiology; D012162:Retinal Degeneration / Q000503:physiopathology*; D018709:Statistics, Nonparametric; D014795:Visual Pathways / Q000502:physiology*
D016194:Receptors, N-Methyl-D-Aspartate; D015636:Magnesium Chloride; D020148:Butyric Acid; D007649:Ketamine