Modulation of ion channels in rod photoreceptors by nitric oxide.
Subcellular compartments in the outer retina of the larval tiger salamander were identified as likely sites of production of nitric oxide (NO), a recently recognized intercellular messenger. NADPH diaphorase histochemistry and NO synthase immunocytochemistry labeled photoreceptor ellipsoids and the distal regions of bipolar and glial cells apposing photoreceptor inner segments, suggesting a role for NO in visual processing in the outer retina. We investigated the actions of NO on several rod photoreceptor ion channels. Application of the NO-generating compound S-nitrosocysteine increased Ca2+ channel current and a voltage-independent conductance, but had no affect on voltage-gated K+ or nonspecific cation currents. Given the steep relation between voltage-dependent Ca2+ influx and photoreceptor synaptic output, these results indicate that NO could modulate transmission of the photoresponse to second order cells.
Kurenny
D E
DE
Neuroscience Research Group University of Calgary, Alberta, Canada.
Moroz
L L
LL
Turner
R W
RW
Sharkey
K A
KA
Barnes
S
S
D000594:Amino Acid Oxidoreductases / Q000378:metabolism; D000818:Animals; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D006152:Cyclic GMP / Q000502:physiology; D003545:Cysteine / Q000031:analogs & derivatives / Q000494:pharmacology; D004110:Diltiazem / Q000494:pharmacology; D015640:Ion Channel Gating; D008274:Magnesium / Q000494:pharmacology; D009252:NADPH Dehydrogenase / Q000378:metabolism; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase; D017948:Retinal Rod Photoreceptor Cells / Q000502:physiology*; D026403:S-Nitrosothiols; D014562:Caudata
D015220:Calcium Channels; D026403:S-Nitrosothiols; D009569:Nitric Oxide; C021315:S-nitrosocysteine; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases; D009252:NADPH Dehydrogenase; D004110:Diltiazem; D006152:Cyclic GMP; D008274:Magnesium; D003545:Cysteine