A型肉毒毒素对P物质引发的大鼠离体幽门平滑肌收缩的抑制作用

目的观察A型肉毒毒素(BTX-A)对内、外源性P物质(SP)引发的大鼠离体幽门平滑肌收缩的影响及其可能机制。方法①使用电场刺激诱导幽门平滑肌内源性神经递质释放,诱发平滑肌收缩,用阿托品阻断胆碱能神经后分别观察NK1受体拮抗剂D-Arg1,D-Phe5,D-Trp7,9,Leu11]-SP(APTL-SP)和BTX-A对肌条收缩的影响。②每隔30 min加入SP诱发在不同浓度BTX-A中孵育的幽门平滑肌条收缩,持续记录4 h,观察BTX-A对外源性SP所诱导肌条收缩的抑制作用。结果①电场刺激增加幽门平滑肌收缩振幅、频率和张力,该作用可被阿托品1μmol.L-1不完全抑制,余波可分别被APTL-SP 1μmol.L-1或BTX-A10 kU.L-1抑制,被BTX-A抑制后的余波不能再被APTL-SP进一步抑制。②分别用BTX-A4和10 kU.L-1孵育幽门平滑肌条,每隔30 min加入SP 1μmol.L-1,连续观察4 h,SP诱导的收缩张力均随时间逐渐降低,4 h时BTX-A4kU.L-1组收缩张力为给BTX-A前SP诱发张力的(73.4±11.5)%,10 kU.L-1组为(25.1±8.1)%。结论BTX-A对外源性SP和电场刺激诱发的内源性SP引起的离体幽门平滑肌收缩具有抑制作用。

Inhibitory effect of botulinum toxin type A on substance P induced contractile response in pyloric smooth muscles in rats in vitro

AIM To investigate the effect of botulinum toxin type A (BTX-A) on endo- and exogenous substance P (SP) induced contractility of the strips isolated from pyloric smooth muscle in rats. METHODS ① Electrical field stimulation (EFS) was used to induce contraction of pyloric circular muscle strips incubated in Kreb bicarbonate buffer via enhancing neurotransmitter release. ［D-Arg¹, D-Phe⁵, D-Trp^7,9, Leu¹¹］-substance P (APTL-SP), an antagonist of NK₁-receptor, and BTX-A was administrated, respectively, following atropine treatment for observing the inhibitive effect of BTX-A on the contractile response to endogenous SP. ② Pyloric smooth muscle strips were incubated in 4 and 10 kU·L^-1 BTX-A, respectively, SP was subsequently added once every 30 min, and recorded the alteration of contraction for 4 h in order to estimate the inhibitory effect of BTX-A on exogenous SP induced contractile response. RESULTS ① Pyloric strips contractility was enhanced including the amplitude, frequency and tension by EFS. The EFS-induced pyloric contractile response was inhibited partly by atropine (1 μmol·L^-1), an antagonist of cholinergic muscarinic receptor. The residual contractility in pyloric muscle strips was further decreased by subsequent administration of APTL-SP 1 μmol·L^-1, or BTX-A 10 kU·L^-1. ② The pyloric muscle strips were incubated with BTX-A 4 or 10 kU·L^-1 for 4 h, and SP 1 μmol·L^-1 was subsequently added once every 30 min during 4 h. SP-induced contractile response was gradually decreased with time, and reduced to (73.4±11.5)% and (25.1±8.1)% in BTX-A 4 and 10 kU·L^-1 groups, respectively, at the end of 4th hour compared with before treatment. CONCLUSION The contractility of the pyloric smooth muscle strips induced by endogenous and exogenous SP can be inhibited by BTX-A.