AJP - Regulatory, Integrative and Comparative Physiology, Vol 258, Issue 3 578-R590, Copyright © 1990 by American Physiological Society
Ultradian adrenocortical and circulatory oscillations in conscious dogs
L. A. Benton and F. E. Yates
Department of Medicine, University of California, Los Angeles 90025.
We examined adrenal blood flow, cortisol secretion rate, concentration of
cortisol in adrenal venous blood, mean arterial blood pressure, and heart
rate in unrestrained conscious dogs, sampling at 15-20 s, 5 min, or 10 min
during experiments lasting from 30 min to 8 h. Time history analysis
designed for short, noisy time series detected three significant ultradian
oscillatory periods: approximately 3, 6, and 90 min. Circulatory variables
(systemic mean arterial pressure, heart rate, and adrenal blood flow)
showed all three. Cortisol secretion rate showed the 3- and 90-min
oscillations but not the 6-min oscillation. Adrenal glucocorticoid
secretion rate and adrenal blood flow were not strongly coupled. However,
at one extreme of blood flow (close to zero) and at the opposite extreme
(very high blood flow stimulated by adrenocorticotropic hormone) adrenal
blood flow and cortisol secretion were tightly coupled. In the normal
physiological range, the multiperiodic, rhythmic organization of
circulatory variables and adrenal glucocorticoid function arises from
independent or only weakly coupled oscillators, not necessarily
harmonically related, manifesting near-periodicity with wobble and
intermittency.
