title: α,β-meATP mimics the effects of the purinergic neurotransmitter in the human and rat colon.
abstract: The purine receptor involved in inhibitory responses in the gastrointestinal tract has been recently identified. P2Y1 receptor activation mediates the fast component of the inhibitory junction potential (IJPf) and the non-nitrergic relaxation. The aim of the present work has been to investigate which purinergic agonist better mimics endogenous responses. We used different agonist and antagonist of P2 receptors. Contractility and microelectrode experiments were used to compare the effects of exogenously added purines and electrical field stimulation (EFS)-induced nerve mediated effects in rat and human colonic strips. In rat colon, the IJPf and EFS-induced inhibition of contractions were concentration-dependently inhibited by the P2Y1 antagonist MRS2500 but not by iso-PPADS or NF023 (P2X antagonists) up to 1 μM. In samples from human colon, EFS-induced inhibition of contractions was inhibited by either MRS2500 or apamin (1 μM) but not by iso-PPADS. In both species, α,β-meATP, a stable analog of ATP, caused inhibition of spontaneous contractions. α,β-meATP effect was concentration-dependent (EC50: 2.7 μM rat, 4.4 μM human) and was antagonized by either MRS2500 or apamin but unaffected by P2X antagonists. ATP, ADP, β-NAD and ADP-ribose inhibited spontaneous contractions but did not show the same sensitivity profile to purine receptor antagonists as EFS-induced inhibition of contractions. The effect of α,β-meATP is due to P2Y1 receptor activation leading the opening of sKca channels. Accordingly, α,β-meATP mimics the endogenous purinergic mediator. In contrast, exogenously added putative neurotransmitters do not exactly mimic the endogenous mediator. Quick degradation by ecto-nuclease or different distribution of receptors (junctionally vs extrajunctionally) might explain these results.
authors.affiliation: Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: Míriam
authors.initials: M
authors.lastname: Martínez-Cutillas
authors.affiliation: Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: Víctor
authors.initials: V
authors.lastname: Gil
authors.affiliation: Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, (CIBERehd), Instituto de Salud Carlos III, Barcelona, Spain.
authors.forename: Diana
authors.initials: D
authors.lastname: Gallego
authors.affiliation: Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: Noemí
authors.initials: N
authors.lastname: Mañé
authors.affiliation: Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, (CIBERehd), Instituto de Salud Carlos III, Barcelona, Spain; Fundació de Gastroenterologia Dr Vilardell and Department of Surgery, Hospital de Mataró, Mataró, Barcelona, Spain.
authors.forename: Pere
authors.initials: P
authors.lastname: Clavé
authors.affiliation: Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Barcelona, Spain; Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, (CIBERehd), Instituto de Salud Carlos III, Barcelona, Spain.
authors.forename: María Teresa
authors.initials: MT
authors.lastname: Martín
authors.affiliation: Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Barcelona, Spain; Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, (CIBERehd), Instituto de Salud Carlos III, Barcelona, Spain. Electronic address: marcel.jimenez@uab.es.
authors.forename: Marcel
authors.initials: M
authors.lastname: Jiménez
mesh_terms: D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D000368:Aged; D000818:Animals; D001030:Apamin / Q000494:pharmacology; D003106:Colon / Q000187:drug effects* / Q000502:physiology; D003838:Deoxyadenine Nucleotides / Q000494:pharmacology; D004558:Electric Stimulation; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D058913:Purinergic Agonists / Q000494:pharmacology*; D058919:Purinergic P2 Receptor Antagonists / Q000494:pharmacology*; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D017207:Rats, Sprague-Dawley; D058472:Receptors, Purinergic P2Y1 / Q000502:physiology*; D013498:Suramin / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: C495475:2-iodo-N(6)-methyl-(N)-methanocarba-2'-deoxyadenosine-3',5'-bisphosphate; D003838:Deoxyadenine Nucleotides; C105374:NF023; D058913:Purinergic Agonists; D058919:Purinergic P2 Receptor Antagonists; D058472:Receptors, Purinergic P2Y1; C077792:pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid; D001030:Apamin; D011732:Pyridoxal Phosphate; D013498:Suramin; D000255:Adenosine Triphosphate; C002630:alpha,beta-methyleneadenosine 5'-triphosphate
keywords: Colonic contractility; Junction potential; P2Y(1) receptors; Purines; Smooth muscle