Development of the defecation pacemaker using artificial muscle

1. 自然排便时结肠和肛肠的运动模式。(1)结肠巨大收缩向直肠的迁移(2)直肠舒张-收缩顺序(3)肛门括约肌舒张在排便过程中起重要作用。结肠和肛肠对第一或第二骶神经电刺激的反应(1)结肠显示向远端扩张的收缩。(2)直肠松弛或收缩。(3)内肛门括约肌放松。这些反应与自然排便时观察到的运动模式相似。智能凝胶作为人工肛门括约肌的可能性该智能凝胶是由甲基丙烯酸酯和硬脂酰丙烯酸酯自由基聚合制备的。在38ºC温度下，其力学性能发生可逆转变。在35ºC时，凝胶的模量和弹性都很高，但在40ºC时，凝胶可以通过低力得到很高的拉伸。即智能凝胶可以表现出与肌肉相似的力学行为。管状人工肛门括约肌1根，直径2.0 cm；2.0厘米长是由凝胶制成的。狗的结肠被拉了出来。结肠的巨大收缩推动粪便物质并扩大人工括约肌以在40℃的温度下排出粪便。当结肠被清空时，括约肌恢复到原来的形状。在35ºC的温度下，收缩不会使凝胶变宽，也不会排出凝胶。这些发现提示了两种可能的系统来控制排便和保持自制。(1)骶神经刺激器用于中枢神经系统问题患者的诱导排便。(2)检测结肠剧烈收缩的同时加热凝胶的起搏器系统，适用于肛肠功能丧失的患者。

1. Motility patterns of the colon and anorectum during spontaneous defecation.(1) Migration of giant contraction of the colon to the rectum (2) rectal relaxation-contraction sequence (3) anal sphincter relaxation play important roles during defecation.2. Responses of the colon and anorectum to the first or second sacral nerve electric stimulation(1) The colon shows contractions propagated distally. (2) The rectum isrelaxed or contracted. (3) The internal anal sphincter is relaxed. These responses are similar to the motility patterns observed during spontaneous defecation.3. Possibility of the intelligent gel as an artificial anal sphincter The intelligent gel is prepared by the radical polymerization of methylacrylate and stearylacrylate. It exhibits the reversible transition of mechanical properties by the change of temperature at 38ﾟC.While the modulus and elasticity of this gel is very high and low, respectively, at 35ﾟC, it can be extended highly by the low force at 40ﾟC.Namely the intelligent gel can show the similar mechanical behavior as the muscle. A tube shaped artificial anal sphincter 2.0 cm in diameter ; 2.0 cm long is made of the gel. The canine colon is pull through it. The giant contractions of the colon propel the fecal material and widen the artificial sphincter to evacuate it at a temperature 4OﾟC.The sphincter returns to the original shape when the colon is emptied. The contraction fails to widen the gel and the contents is not expelled at a temperature 35ﾟC.These findings suggest two possible systems to control defecation and to maintain continence.(1) The sacral nerve stimulator to induce defecation for the patients with central nervous system problems.(2) The pacemaker systems, which detect the giant contraction of the colon and heat the gel simultaneously for the patients who, loosed the function of the anorectum.