Differential sensitivity of a and c nerve fibres to long-acting amide local anaesthetics

Abstract

The differential sensitivities of A β, A δ and C fibres of rat vagus nerve to bupivacaine, etidocaine and AL-381 were studied in vitro. In A β fibres, at 35-37°C, 50μmole litre-1of the drugs had similar effect on the action potential amplitude, while at greater concentrations (100 and 200 μmole litre-1) the greatest mean depression of amplitude was seen with etidocaine (n.s.) AL-381 had the most marked effect on the A δ potentials, and it appeared that it was about twice as potent as the others in blocking these fibres. Etidocaine 100 μmole litre-1 was more depressant than the same dose of bupivacaine. The C fibres were blocked most rapidly by AL-381, while etidocaine had the least effect © 1983 The Macmillan Press Ltd.