AJP - Heart and Circulatory Physiology, Vol 249, Issue 4 807-H813, Copyright © 1985 by American Physiological Society
Cardiopulmonary blood volume and plasma renin activity in normal and hypertensive humans
G. M. London, A. P. Guerin, J. D. Bouthier, A. M. London and M. E. Safar
Plasma renin activity (PRA) and systemic and forearm hemodynamics were
studied during acute changes in cardiopulmonary blood volume and central
venous pressure in 20 subjects, including 9 normotensive controls and 11
essential hypertensive patients of the same age. Changes in cardiopulmonary
blood volume and central venous pressure were induced by a "head-down" tilt
and thigh-cuff inflation. Blood pressure, pulse pressure, and heart rate
did not change during cardiopulmonary blood volume variations, whereas
significant changes in cardiac output, forearm blood flow, and PRA were
observed. A significant negative correlation between cardiopulmonary blood
volume (CPBV) and PRA existed, and slope of this correlation of delta
PRA/delta CPBV was estimated as a sensitivity index of control of renin
release. Sensitivity of neural control of renin release was not
statistically different in normal subjects and hypertensive patients. In
two groups, sensitivity of this reflex mechanism similarly decreased with
age. Aging seems to be an important factor influencing the sensitivity of
neural control of renin release, both in normal and essential hypertensive
humans.
