The Effect Of Intravenous Anesthetics On Isolated Rabbit's Tracheal Smooth Muscle And The Possible Mechanism

Experiment1The effect of propofol on isolated rabbit's tracheal smooth muscle and the possible mechanismObjective To investigate the direct effects of propofol on tracheal smooth muscle tension and the possible mechanism. Methods Japanese rabbits weighing 2000~3000g were executed and the underside of tracheal was removed and placed in modified Kreb's solution balanced with 95%O2 and 5%CO2 After removal of surrounding connective tissue and fat, the tracheal was cut into strips 6~8xl2~15mm.Tracheal strips were suspended in a 37癈 bath of Kreb's solution which was continuously balanced with 95%O2 and 5%CO2 One end of the strips was fixed and the other end was connected to a tension monitor through a tension transducer. Tracheal stips of each animal were divided into six groups in random: group(I^ group(n)> grouptuTK group(Tv> group(V) and groupCVT). The effects of propofol (at concentrations of 10~2 > 2.5xlO~2> 5*10"2 and lO^mg-mT1 )on tracheal strips which were precontracted with acetylcholineClO^mol-mT1) was measured in group I. In group n~rV,before different concentrations of propofol were added, the strips were pretreated with ffldothdinOOrWl-mT1) or L-NAMEOO^mol-ml"1) or methylene blue(10' 'mol-ml'1) or verapamilClO^mol-rnT1) or gttbenclamideOO^mol-mT1). Results Propofol at the concentrations of 2.5x10"2> 5xlO"2and lO^mg-mT1 produced relaxation in tracheal strips .When pretreated with glibenclamide, the effects of relaxation in tracheal strips were depressed partially(P sGC or VOCS channels. The effect is related to the modulation of KATP channels.