PMID: 3752482Jun 1, 1986Paper

Differential block of peripheral nerve fibers: the effect of lidocaine and potassium deficiency

Der Anaesthesist
F Schimek, B R Fink

Abstract

The combined effects of lidocaine and lack of glucose and potassium on conduction in A and C axons were investigated in vitro in rabbit vagus nerve. Extinction times of compound action potentials of A and C axons were determined in glucose and potassium deficient medium in the absence (group I, n = 6) or presence (group III, n = 6) of 0.1 mmol/l lidocaine hydrochloride. In group I, A fibers lost excitability within 120 +/- 9 min (mean +/- SEM) and the C axons within 133 +/- 6 min. In group III lidocaine prolonged significantly extinction times of both A and C axons (p less than 0.001); however, the conduction ceased in the unmyelinated (C) axons about 120 min later than in the myelinated (A) ones (p less than 0.05). In group II (n = 6) nerves were exposed to lidocaine for the same length of time as group I; these nerves exhibited an amplitude depression of the A and C potentials of less than 50%. In group IV, where 2 or 4 mmol/l KCl was present (n = 6 with each concentration) but no lidocaine, the extinction times decreased; the decrease was statistically significant for C axons but not for A axons. The analysis of nerve core electrolytes at the end of the exposures revealed the highest sodium and the lowest potassium contents ...Continue Reading

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