Cyclic GMP in lateral eyes of the horseshoe crab Limulus.
In Limulus photoreceptors, light induces a depolarization. The gating mechanism of the cation channels involved is not understood but evidence exists that cyclic nucleotides may act as ligands. Using an antiserum against a cGMP-protein conjugate, we found strong immunoreactivity localized to the light-sensitive rhabdoms of lateral eye photoreceptors. In homogenated tissue, the cGMP concentration was on average 0.2 pmol/mg retinal tissue protein both in light- and dark-adapted eyes. Phosphodiesterase inhibitors caused a 2-3-fold increase in the cGMP level. Despite our failure to detect a light dependence of the cGMP concentration, these results support the proposed role of cGMP in Limulus phototransduction.
Dorlöchter
M
M
Inst. für Biologie II, RWTH Aachen, 52074, Aachen, Germany. m.dorloechter@uni-bonn.de
de Vente
J
J
D000221:Adaptation, Ocular / Q000502:physiology; D000818:Animals; D006152:Cyclic GMP / Q000032:analysis / Q000378:metabolism*; D006737:Horseshoe Crabs / Q000502:physiology*; D008297:Male; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D017956:Photoreceptor Cells, Invertebrate / Q000187:drug effects / Q000502:physiology*; D011863:Radioimmunoassay; D014785:Vision, Ocular / Q000502:physiology
D010726:Phosphodiesterase Inhibitors; D006152:Cyclic GMP