AJP - Regulatory, Integrative and Comparative Physiology, Vol 243, Issue 3 318-R328, Copyright © 1982 by American Physiological Society
Meaning of the cardiac output-blood volume relationship in essential hypertension
N. P. Chau, T. G. Coleman, G. M. London and M. E. Safar
This study interprets the cardiac output-blood volume relationship in
essential hypertension. Previous reports indicated that the chronic
volume-flow slope (i.e., the regression coefficient alpha, cardiac output =
alpha blood volume + beta, obtained from steady-state volume and flow) and
the transient volume-flow slope observed during a dextran infusion were
both steeper in essential hypertensives than in normotensives. By applying
the Guyton-Coleman circulatory model to essential hypertension, this
reports demonstrates that: 1) several alterations of the circulatory system
may theoretically change the steady state of volume and flow and generate a
chronic volume-flow relationship. However, only alterations of the kidney
function and of the autonomic nervous system may produce a volume-flow
curve compatible with the available data. 2) As hypertension develops,
vascular resistance and compliance have the greatest influence on the slope
of the chronic volume-flow curve. 3) To account for the observed increase
of this slope in the transition from normotension to essential
hypertension, not only must resistance be increased but also compliance
must be reduced in essential hypertension. The same conclusions are drawn
from the study of the transient volume-flow relationship observed during
the dextran infusion.
