Lentle Roger G, Reynolds Gordon W, Janssen Patrick W M, Hulls Corrin M, King Quinten M, Chambers John Paul
Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand.
Division of Urology, Palmerston North Hospital, Palmerston North, New Zealand.
BJU Int. 2015 Dec;116(6):973-83. doi: 10.1111/bju.13132. Epub 2015 Jun 13.
To characterise the area and movements of ongoing spontaneous localised contractions in the resting porcine urinary bladder and relate these to ambient intravesical pressure (Pves ), to further our understanding of their genesis and role in accommodating incoming urine.
We used image analysis to quantify the areas and movements of discrete propagating patches of contraction (PPCs) on the anterior, anterolateral and posterior surfaces of the urinary bladders of six pigs maintained ex vivo with small incremental increases in volume. We then correlated the magnitude of Pves and cyclic changes in Pves with parameters derived from spatiotemporal maps.
Contractile movements in the resting bladder consisted only of PPCs that covered around a fifth of the surface of the bladder, commenced at various sites, and were of ≈6 s in duration. They propagated at around 6 mm/s, mainly across the anterior and lateral surface of the bladder by various, sometimes circular, routes in a quasi-stable rhythm, and did not traverse the trigone. The frequencies of these rhythms were low (3.15 cycles/min) and broadly similar to those of cyclic changes in Pves (3.55 cycles/min). Each PPC was associated with a region of stretching (positive strain rate) and these events occurred in a background of more constant strain. The amplitudes of cycles in Pves and the areas undergoing PPCs increased after a sudden increase in Pves but the frequency of cycles of Pves and of origin of PPCs did not change. Peaks in Pves cycles occurred when PPCs were traversing the upper half of the bladder, which was more compliant. The velocity of propagation of PPCs was similar to that of transverse propagation of action potentials in bladder myocytes and significantly greater than that reported in interstitial cells. The size of PPCs, their frequency and their rate of propagation were not affected by intra-arterial dosage with tetrodotoxin or lidocaine.
The origin and duration of PPCs influence both Pves and cyclic variation in Pves . Hence, propagating rather than stationary areas of contraction may contribute to overall tone and to variation in Pves . Spatiotemporal mapping of PPCs may contribute to our understanding of the generation of tone and the basis of clinical entities such as overactive bladder, painful bladder syndrome and detrusor overactivity.
描述静息状态下猪膀胱中正在进行的自发性局部收缩的区域和运动，并将其与膀胱内环境压力（Pves）相关联，以加深我们对其产生机制及其在容纳进入尿液过程中所起作用的理解。
我们使用图像分析来量化六只猪离体膀胱前表面、前外侧表面和后表面离散的收缩传播斑块（PPCs）的面积和运动，膀胱体积以小幅度递增。然后我们将Pves的大小和Pves的周期性变化与从时空图得出的参数相关联。
静息膀胱中的收缩运动仅由PPCs组成，这些PPCs覆盖膀胱表面约五分之一，在不同部位起始，持续时间约为6秒。它们以约6毫米/秒的速度传播，主要通过各种有时呈圆形的路径在膀胱前表面和侧面传播，呈准稳定节律，且不穿过三角区。这些节律的频率较低（3.15次/分钟），与Pves的周期性变化频率（3.55次/分钟）大致相似。每个PPC都与一个伸展区域（正应变率）相关，并且这些事件发生在应变更恒定的背景下。Pves的周期幅度和经历PPCs的区域在Pves突然增加后增大，但Pves的周期频率和PPCs的起始频率没有变化。当PPCs穿过膀胱较顺应的上半部分时，出现Pves周期峰值。PPCs的传播速度与膀胱肌细胞中动作电位的横向传播速度相似，且显著大于间质细胞中报道的速度。PPCs的大小、频率和传播速度不受动脉内给予河豚毒素或利多卡因剂量的影响。
PPCs的起源和持续时间影响Pves及其周期性变化。因此，收缩的传播区域而非静止区域可能有助于整体张力和Pves的变化。PPCs的时空映射可能有助于我们理解张力的产生以及诸如膀胱过度活动症、膀胱疼痛综合征和逼尿肌过度活动等临床实体的基础。
