Possible role of thiamine in neuromuscular transmission

Abstract

Pyrithiamine (50 mg/kg), a thiamine antagonist, decreased the muscle twitches of the rat masseter muscle at stimulation frequencies above 1 Hz 40--80 min after an i.v. injection. The post-tetanic potentiation (PTP) induced by nerve stimulation of the masseter muscle was abolished by pyrithiamine. Administration of thiamine restored the muscle twitches at stimulation frequencies above 1 Hz and the PTP. The muscle twitches elicited by direct muscle stimulation were not affected by pyrithiamine treatment. The abolishment of the PTP was accompanied by a decrease in thiamine and thiamine-diphosphate. The pyruvate level in the blood was unchanged after pyrithiamine treatment. Oxythiamine, on the other hand, had no effect on the PTP but increased the pyruvate level in the blood. Fern extract which contains thiaminase I also abolished the PTP--an effect reversible by the addition of thiamine. The frequency-induced depression of the muscle twitches induced by pyrithiamine was similar to the effect of low doses of d-tubocurarine (8 microgram/kg). The results support the hypothesis that thiamine may play a role in neuromuscular transmission.

Ultracytochemical Studies in the Dorsal Root and the Dorsal Root Ganglion Neuron of the Rat Spinal Cord

“…Barchi considered it still possible that thiamine antagonists may interfere with the Na-transport system necessary for the action potential (1). Waldenlind was of the opinion that thiamine was important for the excitability of the nerve terminals by an effect on the active ion transport that was necessary for regeneration and maintenance of the membrane potential (17). Our results concerning the dorsal root do not support the view that thiamine reaches the axon membrane and nerve ending via axoplasmic transport (16), since it was impossible to observe AcPase and TMPase activity in the axoplasmic organelles such as microtubules, neurofilaments and endoplasmic reticulum.…”

Differential Inhibition of the Rhythm and Amplitude of Acetylcholine-Dependent Contraction in the Murine Jejunum and Ileum <i>In Vitro</i> by Thiamin and Quinine

“…A previous study using the smooth muscles of the gastric fundus and circular layer of the distal colon of guinea pigs reported that thiamin evoked depolarization in the smooth muscle strips as well as augmented the amplitude of inhibitory synaptic potentials and postinhibitory depolarization [36]. Furthermore, other studies suggested that thiamin is an integral component of synaptosomal membranes [37][38][39][40]. These findings suggested that thiamin plays a role in the mammalian neuromuscular transmission of ICCs to modulate contractions of the small intestine.…”

Biological functions of thiamine derivatives: Focus on non-coenzyme roles

“…Another study suggested that thiamine is an integral component of synaptomal membranes 29 . A role of thiamine in mammalian neuromuscular transmission has also been suggested in other studies 30 . Taken together, all those data suggest that thiamine may have a specific, coenzyme-independent role in synapses.…”