The Effect Of Taurine On Rat Tracheal Smooth Muscle And Its Possible Mechanism

AIM:To investigate the effects of taurine on tracheal smooth muscles and the underlying mechanisms.METHORDS:The tracheal of rats were carefully dissected and the tension of rat isolated tracheal was recorded with Powerlab systerm.The effect of taurine on the precontraction induced by KC1and ACh was observed in isolated trachea of rats; The inhibitors of potassium channels blockers,eNOS(N-nitro-L-arginine methyl ester), cyclooxygenase(Indometacin)were used to study on the effect of taurine;The effect of taurine on the dose-response curves of the contraction of tracheal smooth muscles induced by KC1and ACh was observed.RESULTS:(1)Taurine (10-80mmolL-1)caused concentration-dependent relaxation in the rat isolated tracheal;(2)Taurine shifted the dose-response curves of KC1and ACh to the right and low unparallelly,which was positively correlated with the concentration of taurine;(3)Glibenclamide (10?mo1-L),an antagonist of ATP sensitive potassium channels (KATP), and tetraethtylamine (lOmmol-L),an antagonist of calcium activated potassium channels (Kca) significantly inhibited the relaxation action of taurine on rat isolated tracheal by KC1.Barium chloride (lmmol-L-1) and4-aminopyridine (lmmol-L-1) did not significantly affected taurine induced relaxation;(4)Taurine inhibited the contraction caused by ACh induced intracellular Ca2+release, which was significant diffrence with control group(p<0.05).Taurine inhibited the contraction depending on extracellular Ca2+,which was no difference with control group (p>0.05);(5)NG-nitro-L-arginine methyl ester(L-NAME,1mmo1-L-1)? indometacin (Indo,10umol-L-1) and propranolo(Pino,10?mo1-L-1) did not significantly affected taurine induced relaxation;(5)Taurine inhibited the contraction caused by ACh induced intracellular Ca2+release, which was significant diffrence with control group(p<0.05).Taurine inhibited the contraction depending on extracellular Ca2+,which was no difference with control group (p>0.05).CONCLUTION:(1)Taurine had an obviously relaxtion effect on the isolated rat tracheal smooth muscle,which was concentration-dependent.(2)The isolated tracheal smooth muscle precontracted by ACh and KC1in rats was weakened by taurine.(3)It is suggested that Kca and KATP may be involved in the relaxtion, not Kv or KK..(4)Aslo,the inhibition of VDCC and intracellular Ca2+release are involved in the relaxtion.(5)The relaxtion had little effect on stimulating ? adrenergic receptors or generating No.