Department of Physiology, Medical College of Georgia, Augusta, Georgia, USA.
Compr Physiol. 2012 Oct;2(4):2481-94. doi: 10.1002/cphy.c100056.
Chronic blood pressure is maintained within very narrow limits around an average value. However, the multitude of physiologic processes that participate in blood pressure control present a bewildering array of possibilities to explain how such tight control of arterial pressure is achieved. Guyton and Coleman and colleagues addressed this challenge by creating a mathematical model that integrated the short- and long-term control systems for overall regulation of the circulation. The hub is the renal-body fluid feedback control system, which links cardiac function and vascular resistance and capacitance with fluid volume homeostasis as the foundation for chronic blood pressure control. The cornerstone of that system is renal sodium excretory capability, which is defined by the direct effect of blood pressure on urinary sodium excretion, that is, "pressure natriuresis." Steady-state blood pressure is the pressure at which pressure natriuresis balances sodium intake over time; therefore, renal sodium excretory capability is the set point for chronic blood pressure. However, this often is misinterpreted as dismissing, or minimizing, the importance of nonrenal mechanisms in chronic blood pressure control. This article explains the renal basis for the blood pressure set point by focusing on the absolute dependence of our survival on the maintenance of sodium balance. Two principal threats to sodium balance are discussed: (1) a change in sodium intake or renal excretory capability and (2) a change in blood pressure. In both instances, circulatory homeostasis is maintained because the sodium balance blood pressure set point is reached.
慢性血压在平均水平的非常狭窄范围内保持稳定。然而，参与血压控制的众多生理过程呈现出令人眼花缭乱的可能性，解释了如何实现如此严格的动脉血压控制。Gu yton 和 Coleman 及其同事通过创建一个整合短期和长期控制系统的数学模型来应对这一挑战，以全面调节循环。该模型的核心是肾脏-体液反馈控制系统，它将心脏功能和血管阻力与容量以及液体平衡联系起来，作为慢性血压控制的基础。该系统的基石是肾脏排钠能力，它由血压对尿钠排泄的直接影响定义，即“压力利钠作用”。稳态血压是压力利钠作用在一段时间内平衡钠摄入的压力；因此，肾脏排钠能力是慢性血压的设定点。然而，这常常被误解为忽视或最小化了非肾脏机制在慢性血压控制中的重要性。本文通过关注维持钠平衡对我们生存的绝对依赖性，解释了血压设定点的肾脏基础。讨论了两个对钠平衡的主要威胁：（1）钠摄入量或肾脏排泄能力的变化，（2）血压的变化。在这两种情况下，由于达到了钠平衡血压设定点，循环内环境稳定得以维持。
