腺苷及腺苷三磷酸对大鼠离体结肠平滑肌的作用

目的 比较腺苷和腺苷三磷酸对大鼠离体近端结肠纵行平滑肌活动的调节作用.方法 四导生理记录仪记录大鼠近端结肠纵行肌的等长舒张和收缩反应.结果 对于静息状态下的大鼠离体近端结肠纵行肌标本,腺苷无明显影响(P＞0.05).但是,腺苷三磷酸使静息状态下的大鼠离体近端结肠纵行肌产生微弱的舒张反应后续浓度依赖性收缩反应;腺苷三磷酸的上述作用不受神经阻断剂河豚毒素的影响.大鼠离体近端结肠纵行肌标本在五羟色胺或乙酰胆碱预收缩条件下,腺苷和腺苷三磷酸均可产生浓度依赖性舒张反应,但是腺苷引起的舒张反应明显弱于腺苷三磷酸(P＜0.01).结论 在大鼠离体近端结肠纵行肌,腺苷三磷酸可产生舒张反应和收缩反应,而腺苷仅产生舒张反应.

Effects of adenosine and adenosine triphosphate on motility of isolated colon smooth muscle in rats

Objective To compare the effect of adenosine on longitudinal muscle strips isolated from the rat proximal colon with that of adenosine triphosphate(ATP).Methods Isometric relaxant and contractile responses to ATP and adenosine in longitudinal muscle strips of the rat proximal colon were observed.Results At resting tension,ATP produced a weak relaxation followed by a concentration-dependent contractile response in longitudinal muscle strips of the rat proximal colon,however,adenosine had no effect on the same preparation.Tetrodotoxin did not influence the responses to ATP.When the preparations were precontracted with 5-hydroxytryptamine or acetylcholine,Both ATP and adenosine produced relaxant responses in a concentration-dependent manner,however,the relaxant responses to adenosine were much weaker than those to ATP.Conclusion ATP produces contractile responses and relaxant responses in longitudinal muscle strips of the rat proximal colon,while adenosine only produces relaxant responses.