RELATIONSHIP BETWEEN CORONARY HEMODYNAMIC-CHANGES AND THE PHASIC EVENTS OF RAPID EYE-MOVEMENT SLEEP

Previous studies in dogs showed dramatic increases in coronary blood f low associated with episodes of sinus tachycardia during rapid eye mov ement (REM) sleep. The present study demonstrates that 90% of these su rges in heart rate and coronary flow are concentrated during periods o f phasic REM sleep and only 10% in tonic REM sleep. Intensely phasic R EM was distinguished from moderately phasic REM sleep by the degree of phasic eye movement. The surges were three times more frequent during intensely phasic REM than in moderately phasic REM sleep. However, th e magnitudes of heart rate (37% +/- 3%) and coronary flow (25% +/- 3%) surges were unaffected by the specific substage of REM sleep. The inc idence of surge events was almost eleven times greater in epochs of ph asic REM that also contained a muscle twitch than in those that did no t. During REM sleep, muscle twitches accompanying surges were not asso ciated with any additional elevations in coronary flow or myocardial d emand. Our data indicate that the sinus tachycardia-associated surges in coronary flow represent integrated autonomic responses intrinsic to phasic periods of REM sleep in dogs.