title: Increase in cytosolic Ca2+ induced by elevation of extracellular Ca2+ in skeletal myogenic cells.
abstract: Cytoplasmic Ca(2+) concentration ([Ca(2+)](i)) variation is a key event in myoblast differentiation, but the mechanism by which it occurs is still debated. Here we show that increases of extracellular Ca(2+) concentration ([Ca(2+)](o)) produced membrane hyperpolarization and a concentration-dependent increase of [Ca(2+)](i) due to Ca(2+) influx across the plasma membrane. Responses were not related to inositol phosphate turnover and Ca(2+)-sensing receptor. [Ca(2+)](o)-induced [Ca(2+)](i) increase was inhibited by Ca(2+) channel inhibitors and appeared to be modulated by several kinase activities. [Ca(2+)](i) increase was potentiated by depletion of intracellular Ca(2+) stores and depressed by inactivation of the Na(+)/Ca(2+) exchanger. The response to arginine vasopressin (AVP), which induces inositol 1,4,5-trisphosphate-dependent [Ca(2+)](i) increase in L6-C5 cells, was not modified by high [Ca(2+)](o). On the contrary, AVP potentiated the [Ca(2+)](i) increase in the presence of elevated [Ca(2+)](o). Other clones of the L6 line as well as the rhabdomyosarcoma RD cell line and the satellite cell-derived C2-C12 line expressed similar responses to high [Ca(2+)](o), and the amplitude of the responses was correlated with the myogenic potential of the cells.
authors.affiliation: Dipartimento di Istologia ed Embriologia Medica, Università La Sapienza, 00161 Rome, Italy. fabio.naro@uniroma1.it
authors.forename: Fabio
authors.initials: F
authors.lastname: Naro
authors.forename: Vania
authors.initials: V
authors.lastname: De Arcangelis
authors.forename: Dario
authors.initials: D
authors.lastname: Coletti
authors.forename: Mario
authors.initials: M
authors.lastname: Molinaro
authors.forename: Bianca
authors.initials: B
authors.lastname: Zani
authors.forename: Stefano
authors.initials: S
authors.lastname: Vassanelli
authors.forename: Carlo
authors.initials: C
authors.lastname: Reggiani
authors.forename: Anna
authors.initials: A
authors.lastname: Teti
authors.forename: Sergio
authors.initials: S
authors.lastname: Adamo
mesh_terms: D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D003600:Cytosol / Q000378:metabolism*; D005110:Extracellular Space / Q000378:metabolism*; D007425:Intracellular Membranes / Q000378:metabolism; D008564:Membrane Potentials / Q000502:physiology; D024510:Muscle Development / Q000502:physiology*; D018482:Muscle, Skeletal / Q000166:cytology / Q000502:physiology*; D032446:Myoblasts / Q000502:physiology; D009994:Osmolar Concentration; D010766:Phosphorylation; D051381:Rats
chemical_list: D001127:Arginine Vasopressin; D002118:Calcium