Brengelmann George L
Department of Physiology and Biophysics, University of Washington, Seattle, Washington 98195-7290, USA.
J Appl Physiol (1985). 2003 Mar;94(3):849-59. doi: 10.1152/japplphysiol.00868.2002. Epub 2002 Oct 18.
A. C. Guyton pioneered major advances in understanding cardiovascular equilibrium. He superimposed venous return curves on cardiac output curves to reveal their intersection at the one level of right atrial pressure (Pra) and flow simultaneously consistent with independent properties of the heart and vasculature. He showed how this point would change with altered properties of the heart (e.g., contractility, sensitivity to preload) and/or of the vasculature (e.g., resistance, total volume). In such graphical representations of negative feedback between two subdivisions of a system, one input/output relationship is necessarily plotted backward, i.e., with the input variable on the y-axis (here, the venous return curve). Unfortunately, this format encourages mistaken ideas about the role of Pra as a "back pressure," such as the assertion that elevating Pra to the level of mean systemic pressure would stop venous return. These concepts are reexamined through review of the original experiments on venous return, presentation of a hypothetical alternative way for obtaining the same data, and analysis of a simple model.
A. C. 盖顿在理解心血管平衡方面取得了重大进展。他将静脉回流曲线叠加在心脏输出曲线上，以揭示它们在一个右心房压力（Pra）和流量水平上的交点，该交点同时与心脏和血管系统的独立特性相一致。他展示了这一点会如何随着心脏特性（如收缩性、对前负荷的敏感性）和/或血管系统特性（如阻力、总体积）的改变而变化。在系统两个子部分之间负反馈的这种图形表示中，必然有一个输入/输出关系是反向绘制的，即输入变量在y轴上（在这里是静脉回流曲线）。不幸的是，这种形式助长了关于Pra作为“背压”作用的错误观念，比如断言将Pra提高到平均体循环压力水平会阻止静脉回流。通过回顾关于静脉回流的原始实验、提出获取相同数据的一种假设替代方法以及分析一个简单模型，对这些概念进行了重新审视。
