Streng Tomi, Hedlund Petter, Talo Antti, Andersson Karl-Erik, Gillespie James I
Department of Clinical and Experimental Pharmacology, Lund University Hospital, Sweden.
BJU Int. 2006 May;97(5):1094-101. doi: 10.1111/j.1464-410X.2006.06137.x.
To characterize the contractile activity that occurs in the bladder during the filling phase of the micturition cycle (non-micturition contractions, NMCs), which generate transient rises in intravesical pressure not associated with urine flow.
The experiments were conducted using anaesthetized (chloral hydrate) and un-anaesthetized rats. In un-anaesthetized rats bladder contractile activity was measured using an intravesical cannula implanted under full surgical anaesthesia 3 days previously. In the anaesthetized rats the bladder was exteriorized and a cannula inserted through the dome. In these experiments electrical activity within the detrusor was also measured with a suction electrode on the bladder surface. For each rat, the experimental protocol involved filling the bladder at a constant rate (10 mL/h) to evoke micturition cycles, or infusion of a fixed volume and recording made under effective isovolumetric conditions.
In both anaesthetized and un-anaesthetized rats there were transient rises in bladder pressure (0.5-3 cmH2O). In the anaesthetized rats the amplitude of the transients increased throughout the filling phase, with little change in frequency. The phasic NMCs generating these pressure transients were accompanied by electrical changes in the detrusor. In the middle phase of bladder filling the slow pressure changes were accompanied by slow waves of electrical activity which changed in the pressure cycles immediately before micturition to high-frequency low-amplitude signals. In the un-anaesthetized rats there was a period immediately after voiding where there was no activity. As filling proceeded, low-amplitude low-frequency NMCs appeared that gradually increased in frequency and amplitude during the filling phase. However, the frequency of the transients decreased immediately before micturition despite an increase in amplitude. Similar responses were seen during isovolumetric recording.
The present results show the presence of NMCs in the rat bladder, identify volume-dependent changes in the pattern of this activity during the micturition cycle, and show that NMCs are accompanied by electrical changes in the detrusor. The physiological significance of NMCs is not known but it might be linked to the generation of afferent discharge from mechanoreceptors in the wall, so contributing to sensations related to bladder volume.
描述排尿周期充盈期膀胱内发生的收缩活动（非排尿收缩，NMCs），其会引起膀胱内压短暂升高且与尿流无关。
实验使用麻醉（水合氯醛）和未麻醉的大鼠进行。在未麻醉的大鼠中，使用3天前在完全手术麻醉下植入的膀胱内插管测量膀胱收缩活动。在麻醉的大鼠中，将膀胱外置并通过顶部插入插管。在这些实验中，还使用膀胱表面的吸电极测量逼尿肌内的电活动。对于每只大鼠，实验方案包括以恒定速率（10 mL/h）充盈膀胱以诱发排尿周期，或注入固定体积并在有效的等容条件下进行记录。
在麻醉和未麻醉的大鼠中，膀胱压力均有短暂升高（0.5 - 3 cmH₂O）。在麻醉的大鼠中，短暂变化的幅度在整个充盈期增加，频率变化不大。产生这些压力变化的阶段性NMCs伴随着逼尿肌的电变化。在膀胱充盈的中期，缓慢的压力变化伴随着电活动的慢波，在排尿前的压力周期中变为高频低幅信号。在未麻醉的大鼠中，排尿后立即有一段时间无活动。随着充盈的进行，出现低幅低频的NMCs，其在充盈期频率和幅度逐渐增加。然而，尽管幅度增加，但在排尿前短暂变化的频率降低。在等容记录期间也观察到类似反应。
目前的结果表明大鼠膀胱中存在NMCs，确定了排尿周期中这种活动模式的容量依赖性变化，并表明NMCs伴随着逼尿肌的电变化。NMCs的生理意义尚不清楚，但可能与壁内机械感受器传入放电的产生有关，从而有助于与膀胱容量相关的感觉。
