Lang Richard J, Davidson Margret E, Exintaris Betty
Department of Physiology, Monash University, Clayton, Victoria 3800, Australia.
Exp Physiol. 2002 Mar;87(2):129-46. doi: 10.1113/eph8702290.
The cellular mechanisms that underlie the initiation and propagation of the peristaltic contractions, which transport urine from the kidney to the bladder for storage, remain little understood. Extracellular and intracellular microelectrode recordings have identified two populations of smooth muscle cells as well as a population of renal interstitial cells (RICs) that all display spontaneous electrical activity. By analogy with the heart it has been proposed that atypical smooth muscle cells, preferentially located in the very proximal regions of the renal pelvis, generate the essential pacemaker signal. These pacemaker potentials propagate to neighbouring typical smooth muscle cells or RICs to trigger action potential discharge. These action potentials then propagate distally to trigger other bundles of typical smooth muscle cells. The frequency of action potential discharge and contraction decreases as the relative number of RICs and atypical smooth muscle cells compared to typical smooth muscle cells decreases with distance from the renal fornix. It is clear that functional capsaicin-sensitive sensory afferents and the endogenous release of both tachykinins and prostaglandins are essential in the maintenance of normal peristalsis, as well as in monitoring and responding to any chemical or mechanical stimulation. However, the cellular mechanisms underlying the action of these endogenously-released agents remain to be elucidated.
将尿液从肾脏输送至膀胱储存的蠕动收缩的起始和传播所基于的细胞机制，目前仍知之甚少。细胞外和细胞内微电极记录已识别出两类平滑肌细胞以及一群肾间质细胞（RICs），它们均表现出自发电活动。通过与心脏类比，有人提出非典型平滑肌细胞优先位于肾盂的最近端区域，产生基本的起搏信号。这些起搏电位传播至相邻的典型平滑肌细胞或RICs以触发动作电位发放。然后这些动作电位向远端传播以触发其他束状典型平滑肌细胞。随着与典型平滑肌细胞相比，RICs和非典型平滑肌细胞的相对数量随距肾穹窿的距离增加而减少，动作电位发放频率和收缩频率也降低。显然，功能性辣椒素敏感感觉传入神经以及速激肽和前列腺素的内源性释放对于维持正常蠕动以及监测和响应任何化学或机械刺激至关重要。然而，这些内源性释放物质作用的细胞机制仍有待阐明。
