title: P2-purinoceptor-stimulated phosphoinositide turnover in chick myotubes. Calcium mobilization and the role of guanyl nucleotide-binding proteins.
abstract: ATP, a trigger of P2-purinoceptor-mediated polyphosphoinositide (PI) turnover in cultured myotubes, increased cytosolic calcium levels in a time- and dose-dependent manner (quin2 fluorescence). The calcium was released from intracellular stores, as acute addition of 5 mM EGTA was without significant effect. Adenosine 5'-(3-thiotriphosphate) and 5'-adenylyl imidodiphosphate also increased intracellular levels of inositol phosphates (InsP) and cytosolic calcium levels. Treatment with cholera or pertussis toxin of myotube cultures did not affect the P2-purinoceptor-mediated InsP increase although PI turnover in permeabilized myotubes was stimulated by guanosine 5'-(3-thiotriphosphate). The results suggest that myotube P2-purinoceptors trigger PI turnover and increase intracellular free calcium levels, via a mechanism insensitive to ADP-ribosylation, by cholera or pertussis toxin of guanyl nucleotide-binding (G) proteins. However, the presence of a phospholipase C-coupled G-protein was otherwise demonstrated.
authors.affiliation: Unit of Neurochemistry and Neurotoxicology, University of Stockholm, Sweden.
authors.forename: J
authors.initials: J
authors.lastname: Häggblad
authors.forename: E
authors.initials: E
authors.lastname: Heilbronn
mesh_terms: D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology*; D000266:Adenylyl Imidodiphosphate / Q000494:pharmacology; D000634:Aminoquinolines; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D002645:Chickens; D002772:Cholera Toxin / Q000494:pharmacology; D003600:Cytosol / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004533:Egtazic Acid / Q000494:pharmacology; D005456:Fluorescent Dyes; D019204:GTP-Binding Proteins / Q000502:physiology*; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D007700:Kinetics; D009132:Muscles / Q000187:drug effects / Q000378:metabolism*; D037342:Pertussis Toxin; D010716:Phosphatidylinositols / Q000378:metabolism*; D011983:Receptors, Purinergic / Q000502:physiology*; D013050:Spectrometry, Fluorescence; D013873:Thionucleotides / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
chemical_list: D000634:Aminoquinolines; D005456:Fluorescent Dyes; D010716:Phosphatidylinositols; D011983:Receptors, Purinergic; D013873:Thionucleotides; D010566:Virulence Factors, Bordetella; D000266:Adenylyl Imidodiphosphate; C022571:adenosine 5'-O-(3-thiotriphosphate); D016244:Guanosine 5'-O-(3-Thiotriphosphate); D004533:Egtazic Acid; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D002772:Cholera Toxin; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins; C035739:Quin2; D002118:Calcium