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Hattori T.,Research Center for Lifestyle related Disease | Munakata M.,Research Center for Lifestyle related Disease
Clinical and Experimental Hypertension | Year: 2015

Background: Blood pressure (BP) is generally higher in cold than in warm seasons. This seasonal BP change is largely attributable to outdoor temperature changes. However, if such a typical seasonal change is observed in BP measured under a standardized indoor condition remains unclear. Methods: Resting supine BPs and heart rate (HR) were measured under a standardized room temperature during summer and the next winter in 104 untreated men (38.1 ± 4.4 years). Subjects were classified as having normotension (NT group: n=79) or mildly elevated BP (ME group: n=25) according to the summer measurements. Seasonal variation was defined as the difference from winter to summer measurements. We also examined body composition, endocrine parameters, and renal function. Results: Age did not differ in the two groups (37.6 ± 4.2 versus 39.1 ± 4.9 years). The mean seasonal change in systolic BP was 2.7 ± 1.1mmHg for the NT group and -4.6 ± 1.9mmHg for the ME group (p=0.001). Laboratory and outdoor temperatures did not differ between the two groups in either season. HR, noradrenaline, and estimated glomerular filtration rate were significantly higher during winter in the NT group but not in ME group. Conclusions: Typical seasonal change in BP may be masked in mildly elevated BP measured under a standardized indoor condition. The mechanisms are multifactorial. Our data suggest that out-of-office BP measurements are necessary for correctly understanding seasonal BP change especially in individuals with mildly elevated BP. © 2015 Informa Healthcare USA, Inc.

Hattori T.,Research Center for Lifestyle related Disease | Munakata M.,Research Center for Lifestyle related Disease
Industrial Health | Year: 2015

Job strain is a risk factor for hypertension, but it is not fully understood if components of job strain, or job demand or job control per se could be related to blood pressure (BP), and if so, whether the relationship differs between normotension and mildly elevated BP. We examined resting BP, and job stress components in 113 Japanese male hospital clerks (38.1 ± 4.4 yr). Subjects were classified into normotensive (NT) (<130/85 mmHg, n=83) and mildly elevated BP (ME) (≥130/85 mmHg) groups. Diastolic BP (DBP) showed a significant interaction between group and job control level (p=0.013). Subjects with low job control demonstrated higher DBP than those with high job control (89.1 ± 2.1 vs. 82.3 ± 2.3 mmHg, p=0.042) in ME group even after adjustments for covariates while DBP did not differ between low and high job control subjects in NT group. SystolicBP (SBP) did not differ between high and low job control subjects in both groups. Neither SBP nor DBP differed between high and low demand groups in either group. Among job strain components, job control may be independently related to BP in Japanese male workers with mildly elevated BP. © 2015 National Institute of Occupational Safety and Health.

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