The concentration of guanosine 3',5'-cyclic monophosphate (cyclic GMP) has been examined in suspensions of freshly isolated frog rod outer segments using conditions which previously have been shown to maintain the ability of outer segments to perform a light-induced permeability change (presence of calf serum, anti-oxidant, and low calcium concentration). Illumination causes a rapid decrease in cyclic GMP levels which has a half-time approximately 125 ms. With light exposures that bleach less than 100 rhodopsin molecules in each rod outer segment, at least 10(4)-10(5) molecules of cyclic GMP are hydrolyzed for each rhodopsin molecule bleached. Half of the total cyclic GMP in each outer segment, approximately 2 X 10(7) molecules, is contained in the light-sensitive pool. If outer segments are exposed to continuous illumination, using intensities which bleach between 5.0 X 10(1) and 5.0 X 10(4) rhodopsin molecules/outer segment per second, cyclic GMP levels fall to a value characteristic for the intensity used. This suggests that a balance between synthesis and degradation of cyclic GMP is established. This constant level appears to be regulated by the rate of bleaching rhodopsin molecules (by the intensity of illumination), not the absolute number of rhodopsin molecules bleached...
Skip Nav Destination
Article navigation
1 May 1979
Article|
May 01 1979
Amplitude, kinetics, and reversibility of a light-induced decrease in guanosine 3',5'-cyclic monophosphate in frog photoreceptor membranes.
M L Woodruff
M D Bownds
Online ISSN: 1540-7748
Print ISSN: 0022-1295
J Gen Physiol (1979) 73 (5): 629–653.
Citation
M L Woodruff, M D Bownds; Amplitude, kinetics, and reversibility of a light-induced decrease in guanosine 3',5'-cyclic monophosphate in frog photoreceptor membranes.. J Gen Physiol 1 May 1979; 73 (5): 629–653. doi: https://doi.org/10.1085/jgp.73.5.629
Download citation file:
Sign in
Don't already have an account? Register
Client Account
You could not be signed in. Please check your email address / username and password and try again.
Could not validate captcha. Please try again.
Sign in via your Institution
Sign in via your InstitutionSuggested Content
Influence of calcium on guanosine 3',5'-cyclic monophosphate levels in frog rod outer segments.
J Gen Physiol (January,1981)
Guanosine 3',5'-cyclic monophosphate and the in vitro physiology of frog photoreceptor membranes.
J Gen Physiol (May,1977)
Monovalent selectivity of the cyclic guanosine monophosphate-activated ion channel.
J Gen Physiol (July,1990)
Email alerts
Advertisement