Author(s): Misawa S, Kuwabara S, Kanai K, Tamura N, Nakata M, , Misawa S, Kuwabara S, Kanai K, Tamura N, Nakata M,
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Abstract BACKGROUND: In diabetic nerves, activation of the polyol pathway via an aldose reductase and the resulting impairment of the Na(+)-K(+) pump would lead to a decreased transaxonal Na+ gradient and thereby reduced nodal Na+ currents. OBJECTIVE: To investigate whether the aldose reductase inhibitor (ARI) epalrestat improves nodal Na+ currents and nerve conduction in human diabetic neuropathy. METHODS: The authors conducted a 6-month, open clinical trial with an ARI, epalrestat, in 30 patients with mild-to-moderate diabetic neuropathy. The latent addition technique and measurements of the strength-duration time constant were used to estimate nodal persistent Na+ currents in median motor axons. Excitability testing and extensive nerve conduction studies including F-wave analyses were performed before and 1 and 6 months after the initiation of treatment with oral epalrestat. RESULTS: Within a month of the start of treatment, there was a significant improvement in nerve conduction, particularly in conduction times across the carpal tunnel and F-wave latencies. The results of latent addition (p < 0.05) and strength-duration time constant (p = 0.06) suggested increased nodal persistent Na+ currents. At 6 months, nerve conduction continued to improve. CONCLUSIONS: Aldose reductase pathway inhibition could rapidly increase nodal Na+ currents and thereby improve the slowing of nerve conduction, presumably because of a restoration of the membranous Na+ gradient.
This article was published in Neurology
and referenced in Journal of Clinical & Experimental Pharmacology