Abstract: | The action of trimecaine on sodium permeability of the membrane was studied by the voltage clamp method in single nodes of Ranvier. Like procaine, trimecaine was shown to reduce maximal sodium permeability (
Na) and to induce slow sodium inactivation. The slow inactivation arising in the presence of trimecaine was qualitatively very similar to that observed during the action of procaine or a high external potassium concentration. Dose-effect curves were obtained for
Na and slow inactivation and they showed that one molecule of trimecaine reacts with one sodium channel in the mechanism of both these effects. The local anesthetic has greater affinity for the receptor responsible for slow inactivation (equilibrium constants about 0.3·10–3 M for
Na and 0.2·10–14 M for slow inactivation.A. V. Vishnevskii Institute of Surgery, Academy of Medical Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 8, No. 4, pp. 418–425, July–August, 1976. |