Missouri Study Shows Neuromuscular Junction Failure From Low NaV1.4 Contributes to Sarcopenia

The investigators measured compound muscle action potentials and single-fiber electromyography in 40 older adults and aged mice, quantifying neuromuscular junction transmission failure rates that rose from 8 percent in young controls to 34 percent in those over 75. They then assayed NaV1.4 protein by Western blot and immunofluorescence, documenting a 42 percent decline that correlated with grip strength loss. Parallel mouse experiments confirmed the same deficit and showed that the ClC-1 inhibitor ignaseclant increased force output by 19 percent within two weeks.

Prior sarcopenia research emphasized muscle mass loss and motor neuron dropout, yet this work isolates a reversible synaptic defect downstream of both. The finding aligns with earlier Charcot-Marie-Tooth trial data in which the same compound improved strength scores, suggesting a shared mechanism across acquired and genetic neuromuscular decline.

The study remains limited by its small human sample and reliance on cross-sectional rather than longitudinal data. Next steps require a randomized, placebo-controlled trial of ignaseclant in community-dwelling adults with sarcopenia, powered for six-minute-walk distance and fall incidence at 24 weeks.