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EFFECTS OF LIGHT ON CYCLIC GMP METABOLISM IN RETINAL PHOTORECEPTORS
Author(s) -
Krishna G.,
Krishnan N.,
Fletcher R. T.,
Chader G.
Publication year - 1976
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1976.tb10399.x
Subject(s) - cyclic gmp , guanosine , biophysics , cyclic guanosine monophosphate , chemistry , gtp' , adenosine , cyclic nucleotide , visual phototransduction , nucleotide , biochemistry , retinal , biology , enzyme , organic chemistry , nitric oxide , gene
— Guanylate cyclase activity of dark‐adapted bovine rod outer segments demonstrates a biphasic pattern upon exposure to light. By 10 s of illumination, activity is 20% lower than that observed in dark‐adapted outer segments. Activity subsequently increases and then slowly declines to two‐thirds of the original activity after 10 min of illumination. In the presence of GTP or ATP, hydrolysis of cyclic GMP is rapidly enhanced by exposure of outer segments to light; the magnitude of this effect is dependent on the amount of substrate present. The rapid effects of light on synthesis and degradation of cyclic GMP indicate that these reactions may be involved in the visual process. The concentration of guanosine 3′:5′‐cyclic monophosphate (cyclic GMP) is extraordinarily high in dark‐adapted bovine rod outer segments and is at least 100‐fold that of adenosine 3′:5′‐cyclic monophosphate (cyclic AMP). No significant decrease in the level of cyclic GMP or cyclic AMP was observed however upon exposure of dark‐adapted outer segments to light.