Streng Tomi, Santti Risto, Andersson Karl-Erik, Talo Antti
Institute of Biomedicine, Department of Anatomy, University of Turku, Turku, Finland.
BJU Int. 2004 Jul;94(1):138-42. doi: 10.1111/j.1464-4096.2004.04875.x.
To obtain information on the mechanisms of female rat micturition using a model in which pressure was measured in the bladder and distal part of the urethra corresponding to the location of the rhabdosphincter, providing information on the role of the sphincter in opening and closing the urethral lumen.
A micturition reflex was induced in adult anaesthetized (chloral hydrate and urethane) female rats by filling the bladder with saline. Bladder pressure (BP), urethral pressure (UP), electromyography (EMG) of the middle part of the rhabdosphincter, and urinary flow rate in the distal urethra were simultaneously recorded.
There were four phases of the micturition contraction, the second characterized by intraluminal pressure high-frequency oscillations (IPHFOs) of BP. When a non-oscillatory micturition contraction started, the BP increased and exceeded UP for the rest of the micturition contraction. Even though the BP increased during this first phase, the urethral lumen stayed closed. Its opening was indicated by a simultaneous decrease in BP and increase of UP as the fluid flowed from the bladder to the urethra. When the rhabdosphincter closed, as indicated by an EMG-burst of the muscle, the UP declined, bladder pressure increased and the flow ceased. Because of momentary contractions of the rhabdosphincter, the UP and urine flow rate had the same periodicity as the IPHFOs of BP.
The simultaneous recording of the BP, UP, EMG of the rhabdosphincter and urinary flow rate showed the sequence of events during micturition. The rhabdosphincter acts as an 'on-off' switch, causing interruptions in the urinary flow rate.
利用一种模型获取雌性大鼠排尿机制的信息，该模型可测量膀胱及与尿道横纹括约肌位置相对应的尿道远端的压力，以提供有关括约肌在尿道管腔开闭中作用的信息。
通过向成年麻醉（水合氯醛和乌拉坦）雌性大鼠膀胱内注入生理盐水诱导排尿反射。同时记录膀胱压力（BP）、尿道压力（UP）、尿道横纹括约肌中部的肌电图（EMG）以及尿道远端的尿流率。
排尿收缩有四个阶段，第二阶段的特征是膀胱压力出现管腔内压力高频振荡（IPHFOs）。当非振荡性排尿收缩开始时，在排尿收缩的其余阶段膀胱压力升高并超过尿道压力。尽管在第一阶段膀胱压力升高，但尿道管腔保持关闭。当液体从膀胱流向尿道时，膀胱压力同时下降和尿道压力升高表明尿道管腔开放。当横纹括约肌关闭时，如肌肉的肌电图爆发所示，尿道压力下降，膀胱压力升高且尿流停止。由于横纹括约肌的瞬间收缩，尿道压力和尿流率与膀胱压力的IPHFOs具有相同的周期性。
膀胱压力、尿道压力、横纹括约肌肌电图和尿流率的同步记录显示了排尿过程中的一系列事件。横纹括约肌起到“开关”的作用，导致尿流率中断。
