The interaction of the neuromuscular effects between mivacurium and esmolol in rats.
BACKGROUND
To study the neuromuscular interaction between mivacurium and esmolol, we compared the neuromuscular actions of the ED90 dose of mivacurium both in the absence and presence of esmolol infusion.


METHODS
Twelve rats were anesthetized with urethane. Train-of-four stimulation was applied every 12 s to the sciatic nerve, and the electromyogram (EMG) response of the anterior tibial muscle was measured.


RESULTS
The ED50 and ED90 of mivacurium in rats were 144 +/- 7.3 micrograms/kg and 197 +/- 7.7 micrograms/kg, respectively. The maximal EMG depression produced by ED50 of mivacurium decreased significantly with esmolol treatment from 88.2 +/- 2.7% to 83.1 +/- 2.6% after esmolol infusion (p < 0.05). The onset time for 75% EMG depression was much shorter for control (44 +/- 6.3 s) than that of esmolol treatment (78.2 +/- 2.4 s; p < 0.05). There was no difference between their duration.


CONCLUSIONS
The results of this study demonstrated that esmolol does not potentiate the neuromuscular effect of mivacurium but antagonize the maximal neuromuscular block and decrease its onset time in rats.
Cheng
R Y
RY
Department of Anesthesiology, Taipei Municipal Yang Ming Hospital, Taiwan, R.O.C.
Hau
H R
HR
Sun
Y C
YC
Chou
C D
CD
Liao
K C
KC
Chen
C F
CF
Tsai
S K
SK
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D004347:Drug Interactions; D007546:Isoquinolines / Q000494:pharmacology*; D008297:Male; D000077590:Mivacurium; D009469:Neuromuscular Junction / Q000187:drug effects* / Q000502:physiology; D003473:Neuromuscular Nondepolarizing Agents / Q000494:pharmacology*; D011412:Propanolamines / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D000319:Adrenergic beta-Antagonists; D007546:Isoquinolines; D003473:Neuromuscular Nondepolarizing Agents; D011412:Propanolamines; D000077590:Mivacurium; C036604:esmolol