Propofol attenuates ovalbumin-induced smooth muscle contraction of the sensitized rat trachea: inhibition of serotonergic and cholinergic signaling.

Propofol is considered suitable for induction of anesthesia in patients with bronchial asthma. However, the mechanisms of its action on bronchi are not fully understood. We examined the effects of propofol on ovalbumin (OA)-induced contraction of OA-sensitized rat trachea. Male Wistar rats were sensitized by a single intraperitoneal injection of OA 10 microg mixed with aluminum hydroxide, 10 mg, as adjuvant. Fourteen days later, the experiment was performed using the tracheal rings. We observed the effects of ketanserin, a 5-HT2 receptor antagonist, and atropine on OA-induced contraction. Next, the effects of propofol on OA-, serotonin (5-HT)-, acetylcholine-, or electrical field stimulation-induced contractions were observed. OA-induced contraction was 90% attenuated by the combination of ketanserin and atropine. Propofol significantly attenuated OA-induced contraction in a dose-dependent manner. Propofol abolished 5-HT-induced contraction, attenuated acetylcholine-induced contraction, and also almost completely attenuated the enhancement by 5-HT of electrical field stimulation-induced contraction. These results suggest that the mechanism involved in the attenuation by propofol of OA-induced contraction is inhibition of the actions of 5-HT. Propofol should be a useful anesthetic in patients with immunoglobulin E-related asthma.