Coronary and total peripheral resistance changes during sleep in a
porcine model.
Zinkovska, Sophia M., Edward K. Rodriguez, Debra A. Kirby.
Children's Hospital, Harvard Medical School, Boston, MA
APStracts 2:0427H, 1995.
Changes in autonomic tone in the vasculature during sleep may have
important implications for silent ischemia and sudden cardiac death.
Few models exist in which both cardiac output (CO) and coronary blood
flow (CBF) are continuously measured during natural sleep and
autonomic mechanisms assessed. Catheters were chronically implanted
in the aorta to measure mean arterial pressure (MAP), and flow probes
were placed on the ascending aorta and the circumflex coronary artery
of eighteen pigs. Electrodes determined sleep stage as either non
-rapid eye movement (NREM) or rapid eye movement (REM) sleep. The MAP
was 73+/-3 mmHg in the quiet awake state, did not change in NREM, and
decreased to 64+/-2mmHg in REM sleep (p<0.05). In NREM sleep,
heart rate did not change from awake state values of 136+/-8 bpm, but
increased by 5 bpm in REM sleep (p<0.05). Coronary vascular
resistance decreased from awake state values of 2.7+/-0.2 to 2.2+/
-0.2 mmHg/ml/min in REM (p<0.05); total peripheral resistance
decreased from awake values of 0.061+/-0.004 mmHg/ml/min, to 0.050+/
-0.003 in REM sleep (p<0.05). Those changes appear to have been
mediated primarily by reduction of alpha adrenergic activity.
Spectral analysis of heart rate suggests that power in the high
frequency range (a presumed indicator of parasympathetic tone) was
lower in REM sleep than non-REM sleep.
Received 2 March 1995; accepted in final form 31 July 1995.
APS Manuscript Number H201-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 31 October 95