cGMP-dependent kinase regulates response sensitivity of the mouse on bipolar cell.
The visual system can adjust its sensitivity over a wide range of light intensities. Photoreceptors account for some of this adjustment, but there is evidence that postreceptoral processes also exist. To investigate the latter, we pharmacologically mimicked the effects of light stimulation on mouse On bipolar cells, thus avoiding confounding effects of receptoral mechanisms. Here, we report that cGMP selectively enhances responses to dim, but not bright, stimuli through a purely postsynaptic mechanism. This action of cGMP was completely blocked by inhibitors of cGMP-dependent kinase. We propose that cGMP-dependent kinase decreases coupling of the On bipolar cell glutamate receptor to the downstream cascade, thus amplifying small decreases in photoreceptor transmitter levels that would otherwise go undetected by the visual system.
Department of Neuroscience, Albert Einstein College of Medicine, The Rose F. Kennedy Center, Bronx, New York 10461, USA. jsnellma@aecom.yu.edu
Josefin
J
Snellman
Scott
S
Nawy
D000818:Animals; D006152:Cyclic GMP / Q000378:metabolism / Q000494:pharmacology; D017869:Cyclic GMP-Dependent Protein Kinases / Q000502:physiology*; D003624:Darkness; D006162:Guanylate Cyclase / Q000378:metabolism; D015640:Ion Channel Gating; D007527:Isoenzymes / Q000378:metabolism; D008027:Light; D051379:Mice; D008810:Mice, Inbred C57BL; D020030:Nitric Oxide Donors / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D010396:Penicillamine / Q000031:analogs & derivatives* / Q000494:pharmacology; D020419:Photoreceptor Cells, Vertebrate / Q000166:cytology* / Q000201:enzymology* / Q000502:physiology; D018094:Receptors, Metabotropic Glutamate / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism; D014785:Vision, Ocular
D007527:Isoenzymes; D020030:Nitric Oxide Donors; D018094:Receptors, Metabotropic Glutamate; C110881:S-nitro-N-acetylpenicillamine; C113897:metabotropic glutamate receptor 6; D017869:Cyclic GMP-Dependent Protein Kinases; D006162:Guanylate Cyclase; D010396:Penicillamine; D006152:Cyclic GMP