Journal of Applied Physiology, Vol 73, Issue 4 1246-1252, Copyright © 1992 by American Physiological Society
Nocturnal variations in human lower leg subcutaneous blood flow related to sleep stages
J. H. Sindrup, J. Kastrup, P. L. Madsen, H. Christensen, B. Jorgensen and G. Wildschiodtz
Department of Clinical Physiology/Nuclear Medicine, Bispebjerg Hospital, Copenhagen, Denmark.
Nocturnal subcutaneous adipose tissue blood flow rate was measured in the
lower legs of 10 normal human subjects together with systemic arterial
blood pressure, heart rate, and registration of sleep stages under
ambulatory conditions. The 133Xe washout technique, portable CdTe(Cl)
detectors, and a portable data storage unit were used for measurement of
blood flow rates. The sleep recordings were performed with a portable
computerized sleep analysis system. In accordance with the results of
previous studies, a hyperemic blood flow rate phase (mean increase 140%)
for 100 min was observed approximately 60 min after the subjects went to
bed. The moment of onset of the hyperemic phase was closely related to the
moment of onset of the first episode of deep sleep (stages 3 and 4). There
was a significant (P < 0.01) overrepresentation of deep sleep in the
hyperemic phase compared with adjacent phases, and rapid-eye-movement sleep
predominantly occurred in the latter part of the night, when the
subcutaneous blood flow rate was stable. The results of the present study
are in accordance with current theories of the interrelationship between
the thermoregulatory and the arousal state control systems and, thus, might
suggest that the nightly subcutaneous hyperemia represents a
thermoregulatory effector mechanism.
