title: Non-dipping blood pressure variations in adult Kazakhs are derived from decreased daytime physical activity and increased nighttime sympathetic activity.
abstract: Many of the elderly Kazakhs have been found to exhibit non-dipping blood pressure variations (BPV). Such variations are seen in both normotensive and hypertensive Kazakhs. The purpose of this study was (1) to determine whether middle-aged Kazakhs also include large numbers of non-dippers, (2) to compare the characteristics of non-dipping and dipping, and (3) to clarify the mechanisms responsible for non-dipping type BPV by examining the autonomic nervous activity and physical activity. We performed ambulatory blood pressure (BP) monitoring. The subjects were divided into two groups (dipping and non-dipping type). We monitored the subjects' physical activity with accelerometry and assessed their autonomic nerve activity by performing a frequency domain analysis of their heart rate variability (HRV). The power spectral density (PSD) of the HRV was calculated using fast Fourier transformation. We analyzed the systolic blood pressure (SBP) variations with the maximum entropy method (MEM). The dippers and non-dippers accounted for 48% and 52% of the subjects, respectively. MEM analysis revealed that the SBP variations of the non-dippers exhibited a 24 hour periodicity with a very weak PSD as well as an ultradian periodicity. The non-dippers exhibited higher low-frequency/high-frequency (LF/HF) ratio and lower HF/(LF + HF) ratios than the dippers, particularly during the nighttime. In addition, the non-dippers performed less physical activity than the dippers. These differences in cardiac autonomic function and physical activity might contribute to the generation of a weak circadian rhythm in SBP, and thus, ultimately lead to the non-dipping SBP variations observed in non-dipper Kazakhs.
authors.affiliation: a Blood Pressure Center, MJG Cardiovascular Institute , Saitama , Japan .
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kawamura
authors.affiliation: b Department of Cardiology , MJG Cardiovascular Institute , Saitama , Japan .
authors.forename: Yukio
authors.initials: Y
authors.lastname: Ozawa
authors.affiliation: c Department of Cardiology , Kanazawa Medical University , Himi , Japan .
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Izumi
authors.affiliation: d Department of General Medicine , Nihon University School of Medicine , Tokyo , Japan .
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kasamaki
authors.affiliation: e Department of Laboratory Medicine , Nihon University School of Medicine , Tokyo , Japan .
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Nakayama
authors.affiliation: f Department of Medicine , Nippon Dental University , Tokyo , Japan .
authors.forename: Hiromi
authors.initials: H
authors.lastname: Mitsubayashi
authors.affiliation: g Department of Cardiology , Nihon University School of Medicine , Tokyo , Japan , and.
authors.forename: Masakatsu
authors.initials: M
authors.lastname: Ohta
authors.affiliation: h Department of Nutrition , Tokyo Kasei University , Tokyo , Japan.
authors.forename: Yuhei
authors.initials: Y
authors.lastname: Ichimaru
mesh_terms: D061725:Accelerometry; D000328:Adult; D044466:Asian People; D001341:Autonomic Nervous System; D001794:Blood Pressure / Q000502:physiology*; D018660:Blood Pressure Monitoring, Ambulatory; D016022:Case-Control Studies; D002940:Circadian Rhythm / Q000502:physiology*; D003430:Cross-Sectional Studies; D015716:Electrocardiography, Ambulatory; D005260:Female; D006339:Heart Rate; D006801:Humans; D006973:Hypertension / Q000208:ethnology / Q000503:physiopathology; D007623:Kazakhstan; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D044465:White People
keywords: Hypertension; ethnicity; non-dipper; physical activity; sympathetic activity