UNIGE document Scientific Article
previous document  unige:10109  next document
add to browser collection
Title

Inhibition of evoked acetylcholine release: two different mechanisms in the Torpedo electric organ

Authors
Loctin, F.
Published in European Journal of Pharmacology. 1987, vol. 133, no. 2, p. 225-234
Abstract The action of agents inhibiting evoked transmitter release was investigated by analysing the Ca2+ secretion relationship, electrophysiologically and biochemically, and by measuring the stimulation-induced 45Ca accumulation in the tissue. Transmitter release saturated at external Ca2+ concentrations higher than 4 mM, the releasing mechanism probably being the limiting step. Antagonists of Ca2+ entry (Mg2+, Cd2+, diltiazem) decreased the sensitivity of acetylcholine release to Ca2+, acting as competitive inhibitors, and reduced the stimulation-induced 45Ca accumulation. Quinacrine produced similar effects, indicating that it interacts primarily with Ca2+ entry. In contrast, oxotremorine and adenosine depressed transmitter release proportionally at all Ca2+ concentrations, acting as non-competitive inhibitors, and did not modify the stimulation-induced 45Ca accumulation. Their inhibitory effects were additive and reflected a decrease in the quantal content of the responses evoked. It is concluded that both drugs inhibit cholinergic transmission in the electric organ without altering Ca2+ entry into the nerve endings.
Keywords Acetylcholine/ secretionAdenosine/pharmacologyAnimalsCalcium/ metabolismCalcium Channel Blockers/pharmacologyElectric Organ/ drug effects/innervation/metabolismElectric StimulationIon Channels/ drug effects/physiologyMagnesium/pharmacologyOxotremorine/pharmacologyQuinacrine/pharmacologyTorpedo
Identifiers
PMID: 2434349
Full text
This document has no fulltext available yet, but you can contact its author by using the form below.
Structures
Citation
(ISO format)
MULLER, Dominique, LOCTIN, F., DUNANT, Yves. Inhibition of evoked acetylcholine release: two different mechanisms in the Torpedo electric organ. In: European Journal of Pharmacology, 1987, vol. 133, n° 2, p. 225-234. https://archive-ouverte.unige.ch/unige:10109

175 hits

0 download

Update

Deposited on : 2010-08-06

Export document
Format :
Citation style :