Neuromuscular transmission in amyotrophic lateral sclerosis

RA Maselli, RL Wollman, C Leung… - Muscle & Nerve …, 1993 - Wiley Online Library
RA Maselli, RL Wollman, C Leung, B Distad, S Palombi, DP Richman, EF Salazar‐Grueso…
Muscle & Nerve: Official Journal of the American Association of …, 1993Wiley Online Library
The functional and structural characteristics of the neuromuscular junction were studied in
anconeus muscle biopsies of 10 patients with amyotrophic lateral sclerosis (ALS).
Intracellular recordings revealed decreased amplitudes of miniature endplate potentials
(MEPPs). The MEPP frequencies were highly variable in ALS patients but the average
MEPP frequency was not different from that of control patients. The mean quantal content of
endplate potentials (m), the mean quanta available for immediate release (n), and the mean …
Abstract
The functional and structural characteristics of the neuromuscular junction were studied in anconeus muscle biopsies of 10 patients with amyotrophic lateral sclerosis (ALS). Intracellular recordings revealed decreased amplitudes of miniature endplate potentials (MEPPs). The MEPP frequencies were highly variable in ALS patients but the average MEPP frequency was not different from that of control patients. The mean quantal content of endplate potentials (m), the mean quanta available for immediate release (n), and the mean quantal stores (N) were all decreased. In contrast, the mean probability of quantal release (p) was normal and the mean probability of quantal store release (P) was surprisingly high at the majority of ALS endplates. Histologic evidence of denervation and small or absent nerve terminals were observed in all ALS patients. These functional and structural abnormalities of the neuromuscular junction may explain the fatigability and the electromyographic evidence of impaired neuromuscular transmission often encountered in ALS patients. © 1993 John Wiley & Sons, Inc.
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