title: Interaction of αβ-Methylene ATP with the Cholinergic Twitch Response in the Guinea-Pig Ileum.
abstract: In this study, direct effects of the P2X purinoceptor agonist αβ-methylene ATP (αβ-meATP) and effects on the cholinergic twitch response of the electrically stimulated longitudinal muscle-myenteric plexus (LMMP) strip of the guinea-pig ileum, were investigated. αβ-meATP (1, 3, and 10 µmol/l) induced short-lasting contractions on its own, followed by an inhibition of the twitch response during its presence in the organ bath. The inhibitor of small conductance Ca2+-activated K+ (SK) channels, apamin (100 nmol/l), prevented the inhibitory effect of αβ-meATP on the twitch response, whereas tetraethylammonium (300 µmol/l), a blocker of voltage-gated K+ channels and an inhibitor at nicotinic acetylcholine receptors, augmented the inhibitory effect of αβ-meATP on the twitch response. It is concluded, that there is a functional interaction between P2X receptors and nicotinic receptors in the LMMP strip, and that a major part of the excitatory input to the cholinergic motor neuron evoking the twitch response is purinergic and not nicotinergic.
authors.affiliation: Institute of Experimental and Clinical Pharmacology, Medical University Graz, Graz, Austria.
authors.forename: Josef
authors.initials: J
authors.lastname: Donnerer
authors.forename: Ingrid
authors.initials: I
authors.lastname: Liebmann
mesh_terms: D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D001030:Apamin / Q000494:pharmacology; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects* / Q000502:physiology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D018733:Nicotinic Antagonists / Q000494:pharmacology*; D026902:Potassium Channel Blockers / Q000494:pharmacology*; D058911:Purinergic P2X Receptor Agonists / Q000494:pharmacology*; D058469:Receptors, Purinergic P2X / Q000502:physiology; D019789:Tetraethylammonium / Q000494:pharmacology
chemical_list: D018733:Nicotinic Antagonists; D026902:Potassium Channel Blockers; D058911:Purinergic P2X Receptor Agonists; D058469:Receptors, Purinergic P2X; D001030:Apamin; D019789:Tetraethylammonium; D000255:Adenosine Triphosphate; C002630:alpha,beta-methyleneadenosine 5'-triphosphate