Meng En, Young John S, Brading Alison F
Department of Pharmacology, University of Oxford, Oxford, United Kingdom.
Neurourol Urodyn. 2008;27(1):79-87. doi: 10.1002/nau.20456.
To characterize the detrusor muscle of the mouse urinary bladder in order to understand more precisely spontaneous contractile behavior of this organ. This study examined the spontaneous electrical activity and Ca(2+) dynamics of the detrusor smooth muscle and investigated the role of the urothelium.
Detrusor smooth muscle strips were isolated from mouse bladders. The urothelium was either kept intact or removed. Changes in membrane potential were recorded using sharp electrode intracellular recording. To image Ca(2+) dynamics, tissue strips were exposed to 10 microM Oregon Green 488 BAPTA-1 AM for 70 min, and then image series were acquired with a laser-scanning confocal microscope.
(1) Mouse detrusor smooth muscle cells (SMCs) generate nifedipine-sensitive spontaneous action potentials (sAPs) at a low frequency (1.3 +/- 0.9 min(-1), n = 11) in preparations with intact urothelium. This frequency increased when the urothelium was removed (7 +/- 8.3 min(-1), n = 17) (P < 0.05, Student's t test). (2) Frequent ATP-mediated spontaneous depolarizations were recorded in all cells. (3) The frequency of whole cell Ca(2+) flashes of detrusor smooth muscle cells was higher in preparations with the urothelium removed (median 1.2 min(-1), n = 7) than in urothelium denuded preparations (median 0.6 min(-1), n = 7) (P < 0.01, Mann-Whitney U-test).
Spontaneous activity of the mouse detrusor smooth muscles was characterized enabling future comparative work on gene knock-out strains. Evidence suggesting release of an inhibitory factor by the urothelium was apparent.
对小鼠膀胱逼尿肌进行特征描述，以便更精确地了解该器官的自发收缩行为。本研究检测了逼尿肌平滑肌的自发电活动和Ca(2+)动力学，并研究了尿路上皮的作用。
从小鼠膀胱分离出逼尿肌平滑肌条。尿路上皮要么保持完整，要么被去除。使用尖锐电极细胞内记录法记录膜电位变化。为了成像Ca(2+)动力学，将组织条暴露于10 microM Oregon Green 488 BAPTA-1 AM中70分钟，然后用激光扫描共聚焦显微镜采集图像序列。
(1) 在尿路上皮完整的制备物中，小鼠逼尿肌平滑肌细胞(SMCs)以低频(1.3±0.9次/分钟，n = 11)产生硝苯地平敏感的自发动作电位(sAPs)。去除尿路上皮后，该频率增加(7±8.3次/分钟，n = 17)(P < 0.05，Student's t检验)。(2) 在所有细胞中均记录到频繁的ATP介导的自发去极化。(3) 去除尿路上皮的制备物中逼尿肌平滑肌细胞的全细胞Ca(2+)闪烁频率(中位数1.2次/分钟，n = 7)高于去尿路上皮的制备物(中位数0.6次/分钟，n = 7)(P < 0.01，Mann-Whitney U检验)。
对小鼠逼尿肌平滑肌的自发活动进行了特征描述，为未来对基因敲除品系的比较研究奠定了基础。有明显证据表明尿路上皮释放了一种抑制因子。
