Photosensitivity of 8BrcGMP-induced conductance in ROS-excised patches.
Inside-out patches from ROS plasma membranes contain the basic enzymes of the phototransduction cascade. Similar to a native photoreceptor cell, such patches are capable of responding to light, the effect of which suppresses the cGMP-activated current. Photoresponses are observed only in the presence of GTP, whereas ATP essentially accelerates the current recovery to a dark level. Photoresponses are also observed in the presence of 8BrcGMP. Phosphodiesterase (PDE) hydrolyzes 8BrcGMP two orders of magnitude slower than cGMP, so the light inhibition of the 8BrcGMP-induced current cannot be accounted for by PDE activation. It seems that activity of cGMP-gated channels depends not only on cGMP concentration, but is additionally controlled by some other regulatory mechanisms.
Kosolapov
A V
AV
Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region.
Khalifa-Zade
M Ch
MCh
Kolesnikov
S S
SS
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000818:Animals; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000494:pharmacology; D066298:In Vitro Techniques; D008027:Light; D012374:Rod Cell Outer Segment / Q000187:drug effects / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology; D014982:Xenopus laevis
C016276:8-bromocyclic GMP; D006152:Cyclic GMP; D015056:1-Methyl-3-isobutylxanthine