Marsh Donald J, Sosnovtseva Olga V, Mosekilde Erik, Holstein-Rathlou Niels-Henrik
Department of Molecular Pharmacology, Physiology, and Biotechnology, Brown University, Providence, Rhode Island 02912, USA.
Chaos. 2007 Mar;17(1):015114. doi: 10.1063/1.2404774.
The paper presents a study of synchronization phenomena in a system of 22 nephrons supplied with blood from a common cortical radial artery. The nephrons are assumed to interact via hemodynamic and vascularly propagated coupling, both mediated by vascular connections. Using anatomic and physiological criteria, the nephrons are divided into groups: cortical nephrons and medullary nephrons with short, intermediate and long Henle loops. Within each of these groups the delay parameters of the internal feedback regulation are given a random component to represent the internephron variability. For parameters that generate simple limit cycle dynamics in the pressure and flow regulation of single nephrons, the ensemble of coupled nephrons showed steady state, quasiperiodic or chaotic dynamics, depending on the interaction strengths and the arterial blood pressure. When the solutions were either quasiperiodic or chaotic, cortical nephrons synchronized to a single frequency, but the longer medullary nephrons formed two clusters with different frequencies. Under no physiologically realistic combination of parameters did all nephrons assume a common frequency. Our results suggest a greater variability in the nephron dynamics than is apparent from measurements performed on cortical nephrons only. This variability may explain the development of chaotic dynamics in tubular pressure records from hypertensive rats.
本文介绍了一项关于由一条共同的皮质放射状动脉供血的22个肾单位系统中同步现象的研究。假设这些肾单位通过血液动力学和血管传播的耦合相互作用，两者均由血管连接介导。根据解剖学和生理学标准，肾单位被分为几组：皮质肾单位以及具有短、中、长亨利氏袢的髓质肾单位。在每组中，内部反馈调节的延迟参数都有一个随机分量，以表示肾单位间的变异性。对于在单个肾单位的压力和流量调节中产生简单极限环动力学的参数，耦合肾单位的集合表现出稳态、准周期或混沌动力学，这取决于相互作用强度和动脉血压。当解为准周期或混沌时，皮质肾单位同步到单一频率，但较长的髓质肾单位形成两个具有不同频率的簇。在任何符合生理现实的参数组合下，所有肾单位都不会呈现共同频率。我们的结果表明，肾单位动力学的变异性比仅在皮质肾单位上进行测量所显示的要大。这种变异性可能解释了高血压大鼠肾小管压力记录中混沌动力学的发展。
