Effects of volatile anesthetics on canine tracheal smooth muscle constriction in vivo

用比格犬研究了吸入麻醉药是否能逆转5-羟色胺、组胺、乙酰胆碱或迷走神经引起的气管平滑肌收缩。原位等距测量气管平滑肌反应。在对照检查中，发现5-羟色胺是一种非常有效的收缩激动剂。吸入氟烷、异氟醚或七氟醚后，收缩被拮抗，这种作用被认为是对平滑肌本身的直接作用。组胺或乙酰胆碱对气管肌的作用与5-羟色胺相似，吸入挥发性麻醉药后也可逆转上述作用。电刺激颈迷走神经引起的气管平滑肌收缩作用也被挥发性麻醉药拮抗。结论：挥发性麻醉药通过直接作用于平滑肌和间接迷走神经效应减弱气道张力。

Whether the volatile anesthetics could reverse the tracheal smooth muscle constriction induced by serotonin, histamine, acetylcholine or vagal stimulation were studied in beagles. The tracheal smooth muscle response was measured isometrically in situ. In control examinations, serotonin was found to be a very potent contractile agonist. Under the inhalation of halothane, isoflurane or sevoflurane, contraction was antagonazed, and this effect was considered to be the direct action on smooth muscle itself. Histamine or acetylcholine had the similar effect on tracheal muscle to serotonin, and it was also reversed by the inhalation of volatile anesthetics. The contractile effect of tracheal smooth muscle with the electric stimulation of cervical vagal nerve was also antagonized by volatile anesthetics. The conclusion was that the volatile anesthetics weakened the airway tone by both the direct action on the smooth muscle and the indirect vagolitic effect.