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Chronically instrumented cats were used in the investigation of the central and peripheral mechanism of autonomic cardiovascular regulation during rapid eye movement (REM) sleep by monitoring several central nervous system structures as well as cardiovascular parameters with or without selective autonomic blockers. Results reveal that the primary deceleration observed during REM sleep is brought about by the bursting activity of the cardiac vagal efferent.

Rowe, Katharine, Ricardo Moreno, T. Rern Lau, Umesha Wallooppillai, Bruce D. Nearing, Bernat Kocsis, James Quattrochi, J. Allan Hobson, and Richard L. Verrier. Heart rate surges during REM sleep are associated with theta rhythm and PGO activity in cats. Am. J. Physiol. 277 (Regulatory Integrative Comp. Physiol. 46): R843-R849, 1999.--Rapid eye movement (REM) sleep is characterized by periods of profound cardiac autonomic activation evident in heart rate surges in humans and canines. Our goals were to determine whether or not the heart rate surge phenomenon occurs in cats and to characterize concurrent central nervous system activity. Cortical and hippocampal electroencephalogram, electromyogram, electrooculogram, pontogeniculooccipital (PGO) waves, subcutaneous electrocardiogram, and respiration were recorded. Bouts of sinus tachycardia lasting [is greater than or equal to] 3.5 s achieved a rate of 210 beats/min and were present predominantly during REM sleep. Heart rate during the surges rose an average of 26.4% from 132.5 [+ or -] 2.0 beats/min before the surge to 167.5 [+ or -] 2.6 beats/min (P [is less than] 0.001) and returned to 130.7 [+ or -] 2.6 beats/min (P [is less than] 0.001). The heart rate surges were invariably accompanied by increased incidence and frequency of hippocampal theta waves and increased PGO wave frequency and incidence of PGO wave clusters and eye movement clusters. The occurrence of surges was dramatically reduced from 0.11 [+ or -] 0.03 to 0.01 [+ or -] 0.01/15 s of REM sleep (P = 0.02) by atenolol (0.6 mg/kg iv), indicating that the phenomenon is [[Beta].sub.1]-adrenergically mediated. These findings suggest a coupling between central activation of cardiac sympathetic nerves and the generation of hippocampal theta waves and PGO activity. cardiovascular regulation; sympathetic control; hippocampus; eye movements; lateral geniculate nucleus; rapid eye movement; pontogeniculooccipital waves