BACKGROUND: The body temperature of a patient changes changes during general anesthesia and cholinesterase inhibitor is usually administered at the end of general anesthesia to reverse the neuromuscular blocker effect. We tried to evaluate the effect of temperature changes on the contraction of tracheal smooth muscle induced by acetylcholine (Ach) exogenously administered and neostigmine, cholinesterase inhibitor. METHODS: Isolated tracheal preparations(3 mm wide) of rabbit were mounted in organ baths filled with Tyrode's solution. Cumulative dose responses(isometric contractin) of Ach (10-6, 10-5, 10-4