| The Effects of Flumazenil and Verapamil on the Relaxation of Midazolam in Isolated Guinea-pig Tracheal Smooth Muscle. |
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Shin Ok Koh, Ki Jun Kim, Won Oak Kim, Seong Min Cho, Myoung Ok Kim |
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Department of Anesthesiology, Yonsei University College of Medicine, Seoul, Korea. |
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| Abstract |
BACKGROUND
Midazolam relaxes airway smooth muscle. The aim of this study is to evaluate the influence of flumazenil or verapamil on the relaxation effects of midazolam in tracheal smooth muscle of guinea pig.
METHODS
After isolating guinea-pig tracheal preparations, the maximal tracheal tones were induced by 2 10(-7) M carbachol. When tracheal tones stabilized, midazolam was added cumulatively (10(-6), 3 10(-6), 10(-5), 3 10(-5), 10(-4) M, n=14) with or without flumazenil (10(-6) M, n=15) and verapamil (10(-5) M, n=13) to obtain the concentration-relaxation curves, and then the ED50 and ED95 calculated.
RESULTS
Midazolam decreased maximal tracheal smooth muscle tones in concentration-dependent manners. Pretreatment with flumazenil had no effect on the midazolam-induced relaxation. Verapamil enhanced the relaxation effect of midazolam.
CONCLUSIONS
Midazolam relaxes airway smooth muscle and has synergistic effect with calcium channel blocker, verapamil. |
| Key Words:
Airway: tracheal tone; Anesthetics, intravenous: midazolam; Animals: guinea-pig; Muscle: smooth muscle |
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