Korean J Anesthesiol Search


Korean Journal of Anesthesiology 2001;40(4):532-537.
DOI: https://doi.org/10.4097/kjae.2001.40.4.532   
Evaluation of Presynaptic Action of Depolarizing Neuromuscular Blocking Agents with Single Twitch Response in Vitro.
Kyung Ho Hwang, Won Seok Chai, Kyu Sik Kang, Yong Ik Kim, Wook Park, Sung Yell Kim
Department of Anesthesiology, School of Medicine, Soonchunhyang University, Bucheon, Korea.
This study was performed to evaluate the presynaptic effects of depolarizing neuromuscular blocking drugs by using slow and fast frequencies of indirect stimulation on partial twitch depression in vitro.
A rat phrenic nerve hemidiaphragm was dissected and was mounted in an organ bath containing an oxygenated Krebs solution. The phrenic nerve was stimulated supramaximally and the twitch response (0.1 Hz) was stabilized for at least 30 minutes. T200/T1 ratio (twitch height of the 200th stimuli divided by that of the first stimuli) at frequencies of 0.2, 0.5, 1.0, and 2.0 Hz using a drug concentration which provided approximately 20% twitch depression at 0.1 Hz was calculated. To compare T200/T1 ratios with TOF ratios, a 2.0 Hz TOF response was measured immediately after the 200th stimuli at either frequency of stimulation.
T200/T1 ratios produced by succinylcholine (SCC) and decamethonium (C10) were located between alpha-bungarotoxin (ABX) and hexamethonium (C6), however, significant differences among the four drugs were found at 2.0 Hz. The propensity for a decrease in T200/T1 ratios at 2.0 Hz might differ from this study: C6 > C10 > SCC > ABX. T200/T1 ratios at 2.0 Hz were not different from TOF ratios.
It is concluded that small doses of C10 have a greater presynaptic activity than that of SCC, when the observed effects in this study were compared with the result of ABX acting predominantly at postsynaptic receptors and C6 acting predominantly at presynaptic receptors.
Key Words: Neuromuscular relaxants: alpha-bungarotoxin; decamethonium; hexamethonium; succinylcholine; Neuromuscular transmission: twitch response


Browse all articles >

Editorial Office
101-3503, Lotte Castle President, 109 Mapo-daero, Mapo-gu, Seoul 04146, Korea
Tel: +82-2-792-5128    Fax: +82-2-792-4089    E-mail: journal@anesthesia.or.kr                

Copyright © 2024 by Korean Society of Anesthesiologists.

Developed in M2PI

Close layer
prev next