[Cholinergic mechanisms of interneuronal transmission in the retina].

Acetylcholine applied to the isolated perfused retina (frog and man) elicits a slow corneapositive potential. Such an effect of ACh besides the data known from the literature confirms an assumption on cholinergic synaptic transmission within the retina. The retinal potential elicited by ACh depends in its size and time course on definite parameters of the ACh application as well as on the illumination state of the retina: light stimulation diminishes the electrogenic action of ACh, flickering illumination being more effective than steady one. On the other hand electrical responsiveness of the retina to light lowered during the perfusion of the preparation with ACh. The b-wave seems to be the most sensitive part of the ERG and can be abolished completely, thus isolating the component PIII. The mentioned results as well as the data from the literature indicate the synapses between the first and second retinal neurons as the points of ACh action. Experimental results can be interpreted as the consequence of a desensitization of the cholinergic receptors within the retina.