Miftakhov R N, Abdusheva G R, Christensen J
Laboratory of Numerical Methods in Mathematical Physics, Kazan State University, Kazan 420008, Tatarstan, Russia.
J Theor Biol. 1999 Mar 7;197(1):89-112. doi: 10.1006/jtbi.1998.0859.
A complete mathematical model of the periodic myoelectrical activity of a functional unit of the small intestine is presented. Based on real morphological and electrophysiological data, the model assumes that: the functional unit is an electromyogenic syncytium; the kinetics of L-type Ca2+, T-type Ca2+, Ca2+-activated K+, voltage dependent K+and Cl-channels determine the electrical activity of the functional unit; the enteric nervous system is satisfactorily represented by an efferent cholinergic neuron that provides an excitatory input to the functional unit through receptor-linked L-type Ca2+channels and by an afferent pathway composed of the primary and secondary sensory neurons; the dynamics of propagation of the wave of depolarization along the unmyelinated nerve axons satisfy the Hodgkin-Huxley model; the electrical activity of the neural soma reflects the interaction of N-type Ca2+channels, Ca2+-activated K+and voltage dependent Na+, K+and Cl-channels; the smooth muscle syncytium of the locus is a null-dimensional contractile system. With the proposed model the dynamics of active force generation are determined entirely by the concentration of cytosolic calcium. The model describes: the mechanical excitation of the free nerve endings of the mechanoreceptor of the receptive field of the pathway; the electrical processes of the propagation of excitation along the afferent and efferent neural circuits; the chemical mechanisms of nerve-pulse transmission at the synaptic zones; the slow wave and bursting type electrical activity; cytosolic calcium concentration; the dynamics of active force generation. Numerical simulations have shown that the model can display different electrical patterns and mechanical responses of the locus. The results show good qualitative and quantitative agreement with the results of experiments conducted on the small intestine.
本文提出了一个完整的小肠功能单元周期性肌电活动数学模型。基于实际的形态学和电生理数据，该模型假定：功能单元是一个肌源性合胞体；L型钙通道、T型钙通道、钙激活钾通道、电压依赖性钾通道和氯通道的动力学决定了功能单元的电活动；肠神经系统可由一个传出胆碱能神经元充分代表，该神经元通过受体连接的L型钙通道向功能单元提供兴奋性输入，以及由初级和次级感觉神经元组成的传入通路；去极化波沿无髓神经轴突的传播动力学符合霍奇金-赫胥黎模型；神经胞体的电活动反映了N型钙通道、钙激活钾通道以及电压依赖性钠通道、钾通道和氯通道之间的相互作用；该部位的平滑肌合胞体是一个零维收缩系统。利用所提出的模型，主动力产生的动力学完全由胞质钙浓度决定。该模型描述了：通路感受野机械感受器游离神经末梢的机械兴奋；兴奋沿传入和传出神经回路传播的电过程；突触区神经脉冲传递的化学机制；慢波和爆发型电活动；胞质钙浓度；主动力产生的动力学。数值模拟表明，该模型能够展示该部位不同的电模式和机械反应。结果与在小肠上进行的实验结果在定性和定量上都具有良好的一致性。
