催产素对大鼠离体胃平滑肌收缩活动的影响

Effect of oxytocin on the contractile activity of isolated gastric strips in rats

观察催产素（ｏｘｙｔｏｃｉｎ）对大鼠胃不同部位肌条收缩活动的影响． 结果表明：１０ Ｕ·Ｌ－ １催产素可降低胃底纵行肌张力，升高胃体纵行肌，环行肌和胃窦纵行肌条的张力（升高百分率分别为８±８，３２±２０， ６±８），增大胃体和胃窦各肌条的收缩波平均振幅及幽门环行肌的运动指数（增大百分率分别为２７±４１， ６２±３８， １２±１５， ３９±１９， ５３±２９），增快幽门环行肌的收缩频率〔从（１．２±０．３）ｍ ｉｎ－ １ 增至（１．９±０．３） ｍ ｉｎ－ １〕；而１００ Ｕ·Ｌ－ １催产素升高胃体纵行肌和环行肌及胃窦纵行肌张力的同时降低其收缩波平均振幅，增快各肌条的收缩频率． 阿托品和六甲溴铵均不阻断催产素的上述作用． 结果表明催产素可能直接作用于平滑肌细胞，对大鼠离体胃平滑肌收缩活动起兴奋作用．

Motility of gastric strips taken from different regions of rat stomach was simultaneously recorded in 6 tissue chambers to examine the effect of oxytocin. The main results were as follows: 10 U·L -1 oxytocin decreased the resting tension of fundic longitudinal muscles (LM) and increased that of LM and circular muscles (CM) of the body and LM of antrum (the increased percentage was 8±8, 32±20, 6±8, respectively, P<0.05). It also increased the mean contractile amplitude of LM and CM of body and antrum, and the motility index of pylorus (the increased percentage was 27±41, 62±38, 12±15, 39±19, 53±29, respectively, P<0.05), whereas 100 U·L -1 oxytocin decreased the mean contractile amplitude of the body LM and CM and antral LM. Oxytocin 10 U·L -1 increased the contractile frequency of pyloric CM 〔from (1.2±0.3) to (1.9±0.3) min -1 , P<0.05〕, and 100 U·L -1 oxytocin significantly increased those of the body, antral and pyloric strips. Neither hexamethonium bromide nor atropine blocked the effect of oxytocin. It is concluded that oxytocin can stimulate the contractile activity of stomach strips in rats and this action seems to influence directly on smooth muscle cells.