Open AccessInteraction of glutamate- and adenosine-induced decrease of acetylcholine quantal release at frog neuromuscular junction
Author(s) -
S Adámek,
Anastasia Shakirzyanova,
A. I. Malomouzh,
Nikolay Naumenko,
F. Vyskočil
Publication year - 2010
Publication title -
physiological research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.647
H-Index - 70
eISSN - 1802-9973
pISSN - 0862-8408
DOI - 10.33549/physiolres.932024
Subject(s) - glutamate receptor , neuromuscular junction , metabotropic glutamate receptor , adenosine , inhibitory postsynaptic potential , chemistry , metabotropic receptor , stimulation , biophysics , acetylcholine , neurotransmitter , neuroscience , pharmacology , receptor , biology , biochemistry
In a frog neuromuscular preparation of m. sartorius, glutamatehad a reversible dose-dependent inhibitory effect on bothspontaneous miniature endplate potentials (MEPP) and nervestimulation-evoked endplate potentials (EPP). The effect ofglutamate on MEPP and EPP is caused by the activation ofmetabotropic glutamate receptors, as it was eliminated by MCPG,an inhibitor of group I metabotropic glutamate receptors. Thedepression of evoked EPP, but not MEPP frequency was removedby inhibiting the NO production in the muscle by L-NAME and byODQ that inhibits the soluble NO-sensitive guanylyl cyclase. Theglutamate-induced depression of the frequency of spontaneousMEPP is apparently not caused by the stimulation of the NOcascade. The particular glutamate-stimulated NO cascadeaffecting the evoked EPP can be down-regulated also byadenosine receptors, as the glutamate and adenosine actions arenot additive and application of adenosine partially prevents thefurther decrease of quantal content by glutamate. On the otherhand, there is no obvious interaction between the glutamatemediated inhibition of EPP and inhibitory pathways triggered bycarbacholine and ATP. The effect of glutamate on the evokedEPP release might be due to NO-mediated modulation(phosphorylation) of the voltage-dependent Ca2+ channels at thepresynaptic release zone that are necessary for evoked quantalrelease and open during EPP production.