Bastiaanssen E H, Vanderschoot J, van Leeuwen J L
Medical Informatics, Medical Faculty, Leiden University, The Netherlands.
J Theor Biol. 1996 Jun 7;180(3):215-27. doi: 10.1006/jtbi.1996.0098.
To study the control of the lower urinary tract, the state space of the myocybernetic model by Bastiaanssen et al. (1996) is analysed. This model is able to respond to input signals from a neural network and includes descriptions of the muscle dynamics of both the detrusor in the bladder wall and the urethral sphincter. The equilibrium states of the model for constant input signals were found by evaluation of the roots of calculated flow curves. Two types of equilibrium states could be distinguished: (i) the inflow and the outflow of the bladder are both equal to zero and (ii) the bladder in- and outflow are both equal to a prescribed small constant flow from the ureters into the bladder. The first type of equilibrium features a very high bladder pressure, which in vivo could result in a reflux of urine into the ureters. The second type shows a constant loss of urine. For different combinations of constant input signals, several stable equilibrium states of both types were found. The neural controller should avoid these states so that the lower urinary tract fulfils either its storage or its voiding function. Therefore, the trajectory through the state space of a simulated normal filling and micturition event was evaluated here. It appeared that equilibrium states were avoided by rapid changes of the input signals. The behaviour of the model outside the normal trajectory is compared with neurologic urinary tract disorders. Several pathological behaviours are in qualitative agreement with the model predictions.
为研究下尿路的控制，对巴斯蒂安森等人（1996年）的肌控制论模型的状态空间进行了分析。该模型能够对来自神经网络的输入信号做出响应，并包含膀胱壁逼尿肌和尿道括约肌的肌肉动力学描述。通过评估计算出的流量曲线的根，找到了恒定输入信号下模型的平衡状态。可以区分出两种类型的平衡状态：（i）膀胱的流入和流出均等于零；（ii）膀胱的流入和流出均等于从输尿管进入膀胱的规定小恒定流量。第一种平衡状态的特点是膀胱压力非常高，在体内可能导致尿液反流至输尿管。第二种平衡状态表现为持续的尿液流失。对于恒定输入信号的不同组合，发现了两种类型的几种稳定平衡状态。神经控制器应避免这些状态，以便下尿路履行其储存或排尿功能。因此，在此评估了模拟正常充盈和排尿事件通过状态空间的轨迹。结果表明，通过快速改变输入信号可以避免平衡状态。将模型在正常轨迹之外的行为与神经性尿路疾病进行了比较。几种病理行为与模型预测在定性上一致。
