AJP - Regulatory, Integrative and Comparative Physiology, Vol 250, Issue 1 36-R40, Copyright © 1986 by American Physiological Society
Diurnal variations in cardiovascular integration
B. T. Engel
Beat-to-beat heart periods and intra-arterial blood pressures were
monitored continuously for 18 h in each of six monkeys over periods of
several weeks. Means, based on 128-s averages of these functions, were
highly correlated during early evening and daytime periods; however, heart
period was poorly correlated with blood pressure during the evening hours,
although systolic and diastolic pressures were highly correlated, and the
standard deviations of heart period also were highly correlated with the
pressures. These shifts in cardiovascular integration were unexpected and
suggest that the circulation is relatively sensitive to the conditions
under which it is being assessed, and they suggest further that response
relationships observed under one set of conditions may not be comparable to
those measured under another set of conditions.
