Rabbit cone bipolar cells: correlation of their morphologies with whole-cell recordings.
The superfused retinal slice preparation was used to examine the morphology and glutamate-activated whole-cell currents of rabbit bipolar cells. There were six morphologically distinct types of cone bipolar cells and a rod bipolar cell that had axon terminals stratifying in stratum 3 to 5 of sublamina-b. All of these bipolar cell types exhibited an outward current in response to the application of the metabotropic glutamate receptor, mGluR6, agonist AP-4 (APB), and had I/V curves indicative of membrane channel closure. Conversely, there were no currents activated during the application of kainate, the AMPA/kainate receptor agonist. These data demonstrate they were on-bipolar cells. In addition, there were six morphologically distinct cone bipolar cells that stratified in sublamina-a. Every cell with axonal arborizations in stratum 1 and 2 exhibited an inward current when the ionotropic glutamate receptor agonist kainate was applied. This current was blocked by application of the AMPA/kainate receptor antagonist CNQX. These cells also decreased their membrane resistance in response to kainate, a characteristic of the opening of channels within the plasma membrane. Without exception, no cells stratifying in sublamina-a responded to the mGluR6 agonist AP-4, further identifying them as off-bipolar cells.
McGillem
G S
GS
Department of Ophthalmology, University of Alabama at Birmingham, Callahan Eye Foundation Hospital, 35294-0009, USA.
Dacheux
R F
RF
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000818:Animals; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005456:Fluorescent Dyes; D005998:Glycine / Q000031:analogs & derivatives* / Q000494:pharmacology; D007395:Interneurons / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D008856:Microscopy, Fluorescence; D018408:Patch-Clamp Techniques; D017729:Presynaptic Terminals / Q000502:physiology; D011817:Rabbits; D018094:Receptors, Metabotropic Glutamate / Q000037:antagonists & inhibitors / Q000378:metabolism; D017949:Retinal Cone Photoreceptor Cells / Q000166:cytology*; D012235:Rhodamines
D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D005456:Fluorescent Dyes; D018094:Receptors, Metabotropic Glutamate; D012235:Rhodamines; C104331:cyclopropyl-4-phosphonophenylglycine; C113897:metabotropic glutamate receptor 6; C022027:lissamine rhodamine B; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D005998:Glycine