title: Contribution from P2X and P2Y purinoreceptors to ATP-evoked changes in intracellular calcium concentration on cultured myotubes.
abstract: Although the alteration of purinoreceptor pattern on skeletal muscle is known to accompany physiological muscle differentiation and the pathogenesis of muscle dystrophy, the exact identity of and the relative contribution from the individual receptor subtypes to the purinergic signal have been controversial. To identify these subtypes in cultured myotubes of 5-10 nuclei, changes in intracellular calcium concentration and surface membrane ionic currents were detected and calcium fluxes calculated after the application of the subtype-specific agonists 2'3'-O-(benzoyl-4-benzoyl)-ATP (BzATP), 2-methyltio-ADP and UTP. The effectiveness of these agonists together with positive immunocytochemical staining revealed the presence of P2X(4), P2X(5), P2X(7), P2Y(1) and P2Y(4) receptors. siRNA-reduced protein expression of P2X(5), P2X(7) and P2Y(1) receptors was accompanied by reduction in the ATP-evoked calcium transients. Furthermore, anti-P2X(7) siRNA caused a significant drop in the early peak and delayed steady component of the calculated calcium flux. The use of its antagonist, oxidized ATP, similarly to transfection with anti-P2X(7) siRNA caused significant reduction in the agonist-elicited ionic currents I (ATP) and I (BzATP), with a greater drop in the latter. Our results demonstrate that the activation of ionotropic P2X(4), P2X(5) and P2X(7) and metabotropic P2Y(1) and P2Y(4) purinoreceptors participates in forming the calcium transients of multinucleated myotubes.
authors.affiliation: Department of Physiology, Medical and Health Science Centre, University of Debrecen, 98 Nagyerdei krt., P.O. Box 22, Debrecen, 4012, Hungary.
authors.forename: Tamás
authors.initials: T
authors.lastname: Deli
authors.forename: Henrietta
authors.initials: H
authors.lastname: Szappanos
authors.forename: Gyula Péter
authors.initials: GP
authors.lastname: Szigeti
authors.forename: Julianna
authors.initials: J
authors.lastname: Cseri
authors.forename: László
authors.initials: L
authors.lastname: Kovács
authors.forename: László
authors.initials: L
authors.lastname: Csernoch
mesh_terms: D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D005455:Fluorescent Antibody Technique; D007150:Immunohistochemistry; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D018485:Muscle Fibers, Skeletal / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D018408:Patch-Clamp Techniques; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D034741:RNA, Small Interfering / Q000235:genetics; D018048:Receptors, Purinergic P2 / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D058469:Receptors, Purinergic P2X
chemical_list: D020033:Protein Isoforms; D034741:RNA, Small Interfering; D018048:Receptors, Purinergic P2; D058469:Receptors, Purinergic P2X; D000255:Adenosine Triphosphate; D002118:Calcium