Increase in cytosolic Ca2+ induced by elevation of extracellular Ca2+ in skeletal myogenic cells.
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.
Naro
Fabio
F
Dipartimento di Istologia ed Embriologia Medica, Università La Sapienza, 00161 Rome, Italy. fabio.naro@uniroma1.it
De Arcangelis
Vania
V
Coletti
Dario
D
Molinaro
Mario
M
Zani
Bianca
B
Vassanelli
Stefano
S
Reggiani
Carlo
C
Teti
Anna
A
Adamo
Sergio
S
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
D001127:Arginine Vasopressin; D002118:Calcium