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目的:观察A型肉毒毒素对内、外源性乙酰胆碱诱发的大鼠离体幽门平滑肌收缩的作用,并探讨其可能作用机制。方法:利用电场刺激诱发大鼠离体幽门平滑肌释放乙酰胆碱或加入外源性乙酰胆碱诱发肌条收缩,比较A型肉毒毒素与阿托品对该诱发收缩的作用。结果:A型肉毒毒素抑制电场刺激诱发的大鼠离体胃幽门平滑肌的收缩(P<0.001)。阿托品和A型肉毒毒素均抑制乙酰胆碱诱发的大鼠离体胃幽门平滑肌的收缩(P<0.001),但A型肉毒毒素对乙酰胆碱诱发的收缩表现为不完全抑制。结论:A型肉毒毒素抑制电场刺激诱发内源性乙酰胆碱释放所产生的收缩作用,可能其裂解突触前膜上的SNAP-25蛋白而致;A型肉毒毒素抑制外源性乙酰胆碱诱发的肌条收缩作用类似阿托品,但机制尚不明,可能A型肉毒毒素作用于突触后膜受体或者平滑肌上的SNAP-25蛋白,而抑制肌条的收缩。
OBJECTIVE: To observe the effect of botulinum toxin type A on contractile activity of isolated and isolated pyloric smooth muscle in rats induced by acetylcholine and exogenous acetylcholine, and to explore its possible mechanism. Methods: The release of acetylcholine or exogenous acetylcholine in isolated pyloric smooth muscle of rats induced by electric field was used to induce contractions of muscle strips. The effect of botulinum toxin type A and atropine on the induced contraction was compared. Results: Botulinum toxin type A inhibited contraction of gastric pyloric smooth muscle isolated from electric field in rats (P <0.001). Both atropine and botulinum toxin type A inhibited acetylcholine-induced contraction of isolated rat gastric pyloric smooth muscle (P <0.001), but botulinum toxin type A exhibited incomplete inhibition of acetylcholine-induced contraction. Conclusion: Botulinum toxin type A inhibits the contractile effect of endogenous acetylcholine release induced by electric field stimulation, which may result in the cleavage of SNAP-25 protein on presynaptic membrane. Botulinum toxin type A inhibits the exogenous acetylcholine-induced Myoblast contraction similar to atropine, but the mechanism is not yet clear, botulinum toxin type A may act on the postsynaptic membrane receptor or smooth muscle SNAP-25 protein, and inhibit the contraction of muscle strips.