Differential B and C fibre block by an amide- and an ester-linked local anaesthetic.
The relative sensitivity of sympathetic preganglionic and postganglionic axons, B and C fibres, respectively, to two structurally dissimilar local anaesthetics was examined. The concentration of amethocaine (ester-linked tertiary amine) or prilocaine (amide-linked secondary amine) required to reduce the B fibre compound action potential by 50% was one-third of the concentration required to depress the C fibre potential to a similar extent. Both local anaesthetic agents also showed the action potential propagation through B fibres more than through C fibres. Similar results have been reported previously for lignocaine (amide-linked tertiary amine).
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001338:Autonomic Fibers, Postganglionic / Q000187:drug effects*; D001339:Autonomic Fibers, Preganglionic / Q000187:drug effects*; D003864:Depression, Chemical; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D066298:In Vitro Techniques; D011318:Prilocaine / Q000494:pharmacology*; D011817:Rabbits; D013748:Tetracaine / Q000494:pharmacology*
D011318:Prilocaine; D013748:Tetracaine