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Neurology Research International
Volume 2014 (2014), Article ID 946073, 7 pages
http://dx.doi.org/10.1155/2014/946073
Research Article

Partial Block by Riluzole of Muscle Sodium Channels in Myotubes from Amyotrophic Lateral Sclerosis Patients

1Department of Physiology and Pharmacology, Pasteur Institute-Cenci Bolognetti Foundation, Sapienza University, Piazzale Aldo Moro 5, 00185 Rome, Italy
2Department of Neurology and Psychiatry, Sapienza University, Viale dell’Università 30, 00185 Rome, Italy
3Department of Applied Clinical and Biotechnological Sciences, University of L’Aquila, Via Vetoio, Coppito 2, 67100 L’Aquila, Italy
4IIT@Sapienza, Center for Life Nano Science, Viale Regina Elena 291, 00161 Roma, Italy
5IRCCS Neuromed, 86077 Pozzilli, Italy

Received 26 September 2014; Accepted 18 November 2014; Published 8 December 2014

Academic Editor: Jeff Bronstein

Copyright © 2014 Cristina Deflorio et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Denervated muscles undergo fibrillations due to spontaneous activation of voltage-gated sodium (Na+) channels generating action potentials. Fibrillations also occur in patients with amyotrophic lateral sclerosis (ALS). Riluzole, the only approved drug for ALS treatment, blocks voltage-gated Na+ channels, but its effects on muscle Na+ channels and fibrillations are yet poorly characterized. Using patch-clamp technique, we studied riluzole effect on Na+ channels in cultured myotubes from ALS patients. Needle electromyography was used to study fibrillation potentials (Fibs) in ALS patients during riluzole treatment and after one week of suspension. Patients were clinically characterized in all recording sessions. In myotubes, riluzole (1 μM, a therapeutic concentration) reduced Na+ current by 20%. The rate of rise and amplitude of spikes evoked by depolarizing stimuli were also reduced. Fibs were detected in all patients tested during riluzole treatment and riluzole washout had no univocal effect. Our study indicates that, in human myotubes, riluzole partially blocks Na+ currents and affects action potentials but does not prevent firing. In line with this in vitro finding, muscle Fibs in ALS patients appear to be largely unaffected by riluzole.