Differential effects of sleep stage on coronary hemodynamic function.

The sleep-wake cycle results in distinctive patterns of autonomic nervous system activity. The present study examined the effects of rapid eye movement and slow-wave sleep on coronary hemodynamic function in chronically instrumented dogs. Mean arterial blood pressure was measured via a catheter in the aorta, and coronary blood flow was determined with Doppler probes placed around the left circumflex and right coronary artery. Identification of sleep stages was accomplished by means of electrodes implanted via the frontal sinus to record electro-oculogram, electromyogram, and electroencephalogram. Results indicated that during slow-wave sleep there were moderate but significant reductions in heart rate, 9% decreases in left coronary blood flow, and increases in coronary vascular resistance. In rapid-eye-movement sleep, the circumflex coronary blood flow base line returned to awake levels, and there were pronounced, phasic 35% increases in heart rate and 35% increases in coronary blood flow lasting 15-20 s. These surges were eliminated by stellectomy, indicating that they were mediated by the sympathetic nervous system.