Evidence for the involvement of P2-purinoceptors in the cholinergic contraction of the guinea-pig ileum.
In the isolated ileum of the guinea-pig the P2-purinoceptor antagonists PPADS and suramin: (a) strongly inhibited the cholinergic contractile effect of alpha,beta-methylene ATP, (b) did not influence contractions evoked by exogenous acetylcholine (ACh) but, (c) moderately (by about 30%) inhibited cholinergic contractions due to electrical field stimulation (EFS), in a non-additive manner. These results suggest that an endogenous ligand that stimulates P2-purinoceptors (possibly ATP) is involved in the contractile effect of EFS, as a positive modulator of ACh release.
Barthó
L
L
Department of Pharmacology, University Medical School of Pécs, Hungary.
Lénárd
L
L
Maggi
C A
CA
D000109:Acetylcholine / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D004558:Electric Stimulation; D006168:Guinea Pigs; D007082:Ileum / Q000502:physiology*; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D018048:Receptors, Purinergic P2 / Q000502:physiology*; D013498:Suramin / Q000494:pharmacology
D018048:Receptors, Purinergic P2; C077792:pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid; D011732:Pyridoxal Phosphate; D013498:Suramin; D000255:Adenosine Triphosphate; D000109:Acetylcholine; C002630:alpha,beta-methyleneadenosine 5'-triphosphate