Effect of propofol on tracheal smooth muscle isolated from guinea pigs with induced asthma / 中华麻醉学杂志

ABSTRACT

Objective To investigate the effect of different concentrations of propofol on tracheal smooth muscle (TSM) isolated from guinea pigs with induced asthma and the underlying mechanism. Methods Forty-eight guinea pigs of either sex weighing 150-200 g were randomly divided into 2 groups normal group ( n = 20) and asthma group ( n = 28). Asthma was induced with ovoglobulin. The animals were sacrificed by a blow to the head without anesthesia. Trachea was immediately removed and cut into tracheal rings (3-5 mm in length) . 5-7 tracheal rings were prepared from each animal and suspended in organ bath filled with oxygenated (95% O2 , 5% CO2 ) KHB and stretched to an optimal resting tension which was measured by using a force-displacement transducer with a pen recorder. The two groups were further divided into six subgroups control subgroup, 10 % intralipid subgroup and 4 propofol subgroups (10, 30, 100, 300?mol?L-1). The effect of different concentrations of propofol and their interaction with acetylcholine ( Ach ) and ryanodine on contraction of TSM were measured. Results (1) Effect of propofol on resting tension of TSM in normal group propofol had no effect on TSM resting tension, while in asthma group propofol reduced TSM resting tension in a dose-dependent manner. 10% intralipid contracted TSM slightly and insignificantly as compared with control subgroup. (2) Effect of propofol on TSM contraction induced by Ach propofol inhibited TSM contraction induced by Ach in a dose-dependent manner in both normal and asthma group. (3) Effect of propofol preconditioning on TSM contraction induced by Ach pretreatment with propofol 100 and 300?mol?L-1 significantly inhibited TSM contraction induced by Ach in both normal and asthma group as compared with control subgroup. Pretreatment with even propofol 30?mol?L-1 was effective in asthma group. (4) There was no significant difference in propofol-inhibition of TSM contraction induced by Ach with or without ryanodine. Conclusion Pretreatment with clinical doses of propofol can significantly inhibit TSM contraction induced by Ach in guinea pigs with asthma and ryanodine receptor-mediated smooth muscle intracellular Ca2+ release is not involved.