title: T-type alpha 1H Ca2+ channels are involved in Ca2+ signaling during terminal differentiation (fusion) of human myoblasts.
abstract: Mechanisms underlying Ca(2+) signaling during human myoblast terminal differentiation were studied using cell cultures. We found that T-type Ca(2+) channels (T-channels) are expressed in myoblasts just before fusion. Their inhibition by amiloride or Ni(2+) suppresses fusion and prevents an intracellular Ca(2+) concentration increase normally observed at the onset of fusion. The use of antisense oligonucleotides indicates that the functional T-channels are formed by alpha1H subunits. At hyperpolarized potentials, these channels allow a window current sufficient to increase [Ca(2+)](i). As hyperpolarization is a prerequisite to myoblast fusion, we conclude that the Ca(2+) signal required for fusion is produced when the resting potential enters the T-channel window. A similar mechanism could operate in other cell types of which differentiation implicates membrane hyperpolarization.
authors.affiliation: Département de Physiologie, Centre Médical Universitaire, and Division de Recherche Clinique Neuro-Musculaire, Hôpital Cantonal Universitaire, CH-1211 Geneva 4, Switzerland.
authors.forename: P
authors.initials: P
authors.lastname: Bijlenga
authors.forename: J H
authors.initials: JH
authors.lastname: Liu
authors.forename: E
authors.initials: E
authors.lastname: Espinos
authors.forename: C A
authors.initials: CA
authors.lastname: Haenggeli
authors.forename: J
authors.initials: J
authors.lastname: Fischer-Lougheed
authors.forename: C R
authors.initials: CR
authors.lastname: Bader
authors.forename: L
authors.initials: L
authors.lastname: Bernheim
mesh_terms: D002118:Calcium / Q000378:metabolism*; D020747:Calcium Channels, T-Type / Q000378:metabolism*; D002454:Cell Differentiation; D002478:Cells, Cultured; D006801:Humans; D017136:Ion Transport; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D020747:Calcium Channels, T-Type; D002118:Calcium