PRESYNAPTIC EFFECT OF I.V. ANAESTHETIC AGENTS AT THE NEUROMUSCULAR JUNCTION

• Published in: British journal of anaesthesia : BJA Vol. 51; no. 4; pp. 353 - 357
• Main Authors: TORDA, T.A., MURPHY, E.C.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.04.1979; Oxford University Press
• Subjects: Acetylcholine - metabolism; Alfaxalone Alfadolone Mixture - pharmacology; Anesthesia, Intravenous; Animals; Diazepam - pharmacology; Ketamine - pharmacology; Membrane Potentials - drug effects; Mice; Neuromuscular Junction - drug effects; Neuromuscular Junction - physiology; Pregnanediones - pharmacology; Propanidid - pharmacology; Secretory Rate - drug effects; Thiopental - pharmacology
• ISSN: 0007-0912; 1471-6771
• DOI: 10.1093/bja/51.4.353

The effect of Althesin, diazepam, ketamine, propanidid and thiopentone on the release of acetylcholine was tested at the mouse neuromuscular junction. Althesin, diazepam and thiopentone increased the quantal content of the end-plate potential. Ketamine at low concentration (3·6 (μmol litre−11) had a similar effect, but at high concentration (116·7 μmol litre−1) quantal content decreased sharply. Propanidid and cremophor EL did not affect quantal content. The increase in quantal content antagonized the effect of postsynaptic depression on the amplitude of the end-plate potential. The lack of enhancement of acetylcholine release appears to explain the in vitro interaction of propanidid with tubocurarine. The diversity of presynaptic actions of these drugs makes it unlikely that this is an important mechanism in producing anaesthesia.