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Relationship between blood pressure, sleep K-complexes, and muscle sympathetic nerve activity in humans

Item Type:Article
Title:Relationship between blood pressure, sleep K-complexes, and muscle sympathetic nerve activity in humans
Creators Name:Tank, J. and Diedrich, A. and Hale, N. and Niaz, F.E. and Furlan, R. and Robertson, R.M. and Mosqueda-Garcia, R.
Abstract:Stage 2 sleep is characterized by the EEG appearance of "K-complexes" and blood pressure oscillations. K-complexes may be directly related to blood pressure changes or they may reflect central sympathetic activation. We analyzed the temporal relationship among K-complexes, heart rate (HR), blood pressure (BP), and muscle sympathetic nerve activity (MSNA) during sleep in eight healthy volunteers (3 men and 5 women, age 22-41 yr). Most K-complexes presented as single large complexes (56 +/- 20%), followed by single small complexes (15 +/- 14%) and as couplets or triplets (13 +/- 6%). Single large K-complexes were preceded by a baroreflex-mediated increase of MSNA in approximately one-half (55%) of the cases. Detailed analysis of HR, BP, and MSNA was possible in 63 (45%) large single K-complexes not disturbed by preceding baroreflex-related changes. Systolic and diastolic BP and MSNA increased significantly after single events (22.5 +/- 13, 5.2 +/- 2.1, and 6.5 +/- 3.0%). Mean sympathetic baroreflex latency was similar after the single large K-complexes compared with the mean value during stage 2 sleep (1,290 +/- 126 vs. 1,279 +/- 61 ms). The area under the burst was significantly increased after single large K-complexes (median 3.9 vs. 9.0 arbitrary units, P < 0.03). The results support the hypothesis that K-complexes express cortical activation leading to temporary facilitation of sympathetic outflow in a graded fashion. Their functional effects appear to be independent of baroreflex modulation of MSNA in approximately 50% of the cases.
Keywords:Baroreflex, Blood Pressure, Electrocardiography, Electroencephalography, Heart Rate, Reaction Time, Skeletal Muscle, Sleep Stages, Sympathetic Nervous System
Source:American Journal of Physiology Regulatory Integrative and Comparative Physiology
Publisher:American Physiological Society
Page Range:R208-R214
Date:1 July 2003
Official Publication:https://doi.org/10.1152/ajpregu.00013.2003
PubMed:View item in PubMed

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