Fast Ionic Flux Activated by Cyclic GMP in the Membrane of Cattle Rod Outer Segments

Abstract

Guanosine 3/,5′‐monophosphate (3′,5'GMP) activates an influx of calcium ions into vesicles of rod outer segments washed free of water‐soluble proteins and filled with a hihg‐affinity ligand for calcium (EDTA, Arsenazo III, aequorin). Addition of 3′,5′GMP activates calcium inflix without any appreciable delay, studied with methods that resolve 40 ms. A direct interaction between the cyclic nucleotide and an intrinsic membrane component is considered.