Functional expression and properties of the human skeletal muscle sodium channel

Mohamed Chahine, Paul B. Bennett, Alfred L. George, Richard Horn*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

104 Scopus citations

Abstract

Full-length deoxyribonucleic acid, complementary (cDNA) constructs encoding the α-subunit of the adult human skeletal muscle Na+ channel, hSkM1, were prepared. Functional expression was studied by electrophysiological recordings from cRNA-injected Xenopus oocytes and from transiently transfected tsA201 cells. The Na+ currents of hSkM1 had abnormally slow inactivation kinetics in oocytes, but relatively normal kinetics when expressed in the mammalian cell line. The inactivation kinetics of Na+ currents in oocytes, during a depolarization, were fitted by a weighted sum of two decaying exponentials. The time constant of the fast component was comparable to that of the single component observed in mammalian cells. The block of hSkM1 Na+ currents by the extracellular toxins tetrodotoxin (TTX) and μ-conotoxin (μCTX) was measured. The IC50 values were 25 nM (TTX) and 1.2 μM (μCTX) in oocytes. The potency of TTX is similar to that observed for the rat homolog rSkM1, but the potency of μCTX is 22-fold lower in hSkM1, primarily due to a higher rate of toxin dissociation in hSkM1. Single-channel recordings were obtained from outside-out patches of oocytes expressing hSkM1. The single-channel conductance, 24.9 pS, is similar to that observed for rSkM1 expressed in oocytes.

Original languageEnglish (US)
Pages (from-to)136-142
Number of pages7
JournalPflügers Archiv European Journal of Physiology
Volume427
Issue number1-2
DOIs
StatePublished - May 1 1994

Keywords

  • Heterologous expression
  • Human skeletal muscle
  • Sodium channel
  • Xenopus oocytes
  • μ-Conotoxin

ASJC Scopus subject areas

  • Physiology
  • Clinical Biochemistry
  • Physiology (medical)

Fingerprint Dive into the research topics of 'Functional expression and properties of the human skeletal muscle sodium channel'. Together they form a unique fingerprint.

Cite this