Effects of dexmedetomidine on the isolated rat tracheal smooth muscle

Background/Purpose: Intranasally administered dexmedetomidine, a highly selective α2-adrenoceptor agonist, has been found to an effective premedication in children. However, the effect of delivering dexmedetomidine directly into the tracheal smooth muscle through inhalation has not been adequately explored. The objective of this study was to determine the effects of dexmedetomidine on the isolated rat tracheal smooth muscle invitro. Methods: A portion of rat trachea (5mm in length) was mounted in a muscle bath filled with 30mL of Krebs solution at 37°C. The following effects of dexmedetomidine were assessed: (1) effect on the tracheal smooth muscle resting tension, (2) effect on contraction caused by 10^-6M methacholine, and (3) effect on electrically induced tracheal smooth muscle contractions. Results: Dexmedetomidine elicited a negligible effect on the basal tension of the trachea as its concentration was increased. Dexmedetomidine caused a concentration-dependent relaxation in the trachealis muscle precontracted with 10^-6M methacholine, but did not affect the contractile response to electrical field stimulation. Conclusion: The results of this study suggest that high concentrations of dexmedetomidine might have an antispasmodic effect on the tracheal smooth muscle.