Inhibitions Of Propofol On Trachea Smooth Muscle Contraction In Vitro And In Vivo

Objectives: The potential bronchial spasm usually is a very serious circumstance during the induction of general anaesthesia in patients with airway hyper-responsiveness (AHR) diseases, such as upper respiratory infection, asthma, chronic obstructive pulmonary diseases and so on. Because these patients' airways have accentuated responses to external stimuli, and the bronchial asthma may happen during the anaesth process. Propofol, a new generation of venous anesthetic, has been widely used in clinical anesthesia and ICU sedation compared with research abroad. Aim of this paper was to observe the effect of propofol on tracheal smooth muscle contraction, and provide the theory bases for safely using propofol in patients with asthma and AHR.Methods: 1. Guinea pig tracheal strips were incubated in organ baths filled with Krebs-Henseleit solution and supplied with a mixed gas of 95% O₂ and 5% CO₂. The isometric force was measured by Medlab collecting-system. 2. The latent period of asthma induced by histamine (HIS) and acetylcholine (ACh) in guinea pig were measured before and after administrated propofol (1mg/kg) intravenously.Results: 1. Propofol (150 mmol/L, 450 mmol/L ) caused relaxation of isolated trachea muscle strips (TMS) pre-contracted by ACh and HIS, the percentsof relaxation were 24% ±5% and 36% ±6% for ACh and 28% ±6% and 37% ±7% for HIS respectively (all P<0.05) in guinea pigs. Indomethacin, methylene blue, L-NAMA, propranolol and epithelium removal did not affect the inhibitions induced by propofol in trachea smooth muscle, but the presence of glibenclamide partly decreased the relaxation induced by propofol. Propofol could shift the concentration-response curves of ACh and HIS to the rightward. 2. The incubation periods of asthma in guinea pigs were delayed by propofol (1 mg/kg) given...