[Generalized posttetanic changes in the excitatory postsynaptic and acetylcholine-evoked currents in snail neurons]

Heteroreceptor posttetanic changes in excitatory postsynaptic currents (EPSC) and inward currents evoked by the local iontophoretic application of acetylcholine (ACh) on the dorsal surface of PLa3 and PRa3 Helix lucorum neurons were studied. The following changes in the currents were revealed over the course of 1-1.5 h after tetanization. The rhythmical ACh application (0.5-1.0 cps, 10-40 s) evokes potentiation of the orthodromic EPSC. The tetanic orthodromic stimulation of one of the nerves (n. intestinalis, n. pallialis dexter, or n. pallialis sinister; 1-5 cps, 1-2 min) causes the potentiation of the ACh current and also heterosynaptic depression of the EPSC. It is concluded that activation of subsynaptic and nonsynaptic neurotransmitter chemoreceptors evokes the development of generalized posttetanic changes in neuronal responses.