Hypertension does not alter the increase in cardiac baroreflex sensitivity caused by moderate cold exposure Heidi E. Hintsala1, 2*, Antti M. Kiviniemi2, Mikko P. Tulppo2, Heta Helakari3, Hannu Rintamäki4, 5, Matti Mäntysaari1, Karl-Heinz Herzig5, 6, 2, 7, Sirkka KeinänenKiukaanniemi8, 9, 2, Jouni J. Jaakkola1, 2, Tiina M. Ikäheimo1, 2* 1
Center for Environmental and Respiratory Health Research, University of Oulu, Finland,
2
Medical Research Center Oulu, Oulu University Hospital and University of Oulu, Finland,
3
Medical Technology, Faculty of Medicine, University of Oulu, Finland, 4Finnish Institute
of Occupational Health, Finland, 5Institute of Biomedicine, University of Oulu, Finland,
l a n o si
6
Biocenter of Oulu, University of Oulu, Finland, 7Department of Gastroenterology and
Metabolism, Poznan University of Medical Sciences, Poland, 8Center for Life Course Epidemiology and Systems Medicine, University of Oulu, Finland, 9Unit of Primary Health Care, Oulu University Hospital, Finland
i v o r P Submitted to Journal: Frontiers in Physiology Specialty Section: Vascular Physiology ISSN: 1664-042X
Article type: Original Research Article Received on: 29 Jan 2016 Accepted on: 19 May 2016
Provisional PDF published on: 19 May 2016 Frontiers website link: www.frontiersin.org Citation: Hintsala HE, Kiviniemi AM, Tulppo MP, Helakari H, Rintamäki H, Mäntysaari M, Herzig K, Keinänenkiukaanniemi S, Jaakkola JJ and Ikäheimo TM(2016) Hypertension does not alter the increase in cardiac baroreflex sensitivity caused by moderate cold exposure. Front. Physiol. 7:204. doi:10.3389/fphys.2016.00204 Copyright statement: © 2016 Hintsala, Kiviniemi, Tulppo, Helakari, Rintamäki, Mäntysaari, Herzig, Keinänen-kiukaanniemi, Jaakkola and Ikäheimo. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution and reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
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i v o r P
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Hypertension does not alter the increase in cardiac baroreflex sensitivity caused by moderate cold exposure 1 2 3
Heidi E Hintsala1,2, Antti M Kiviniemi2, Mikko P Tulppo2, Heta Helakari3, Hannu Rintamäki4,5, Matti Mäntysaari1, Karl-Heinz Herzig5,6,2,7, Sirkka Keinänen-Kiukaanniemi8,9,2, Jouni JK Jaakkola1,2, Tiina M Ikäheimo1,2*
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Medical Technology, Faculty of Medicine, University of Oulu, Oulu, Finland
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Finnish Institute of Occupational Health, Oulu, Finland
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Institute of Biomedicine, University of Oulu, Oulu, Finland
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Biocenter of Oulu, University of Oulu, Oulu, Finland
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Center for Environmental and Respiratory Health Research, University of Oulu, Oulu, Finland Medical Research Center Oulu, Oulu University Hospital and University of Oulu, Oulu, Finland
l a n o si
Department of Gastroenterology and Metabolism, Poznan University of Medical Sciences, Poznan, Poland
Center for Life Course Epidemiology and Systems Medicine, University of Oulu, Oulu, Finland
i v o r P
Unit of Primary Health Care, Oulu University Hospital, Oulu, Finland
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* Correspondence: Dr. Tiina M. Ikäheimo, Center for Environmental and Respiratory Health Research, P.O. Box 5000, FI-90014 University of Oulu, Finland, Phone: +358 40 5422968, Fax: +358 8 537 5661
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Tiina.Ikä
[email protected]
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Keywords: hypertension, cold temperature, baroreflex, blood pressure, variability
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Abstract
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Exposure to cold increases blood pressure and may contribute to higher wintertime cardiovascular morbidity and mortality in hypertensive people, but the mechanisms are not well established. While hypertension does not alter responses of vagally-mediated heart rate variability to cold, it is not known how hypertension modifies baroreflex sensitivity and blood pressure variability during cold exposure. Our study assessed this among untreated hypertensive men during short-term exposure comparable to habitual winter time circumstances in subarctic areas. We conducted a population-based recruitment of 24 untreated hypertensive and 17 men without hypertension (age 55-65 years) who underwent a whole-body cold exposure (-10°C, wind 3m/s, winter clothes, 15 min, standing). Electrocardiogram and continuous blood pressure were measured to
Hypertension, cold, and baroreflex sensitivity
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compute spectral powers of systolic blood pressure and heart rate variability at low (0.04-0.15 Hz) and high frequency (0.15-0.4 Hz) and spontaneous baroreflex sensitivity at low frequency. Comparable increases in baroreflex sensitivity were detected in hypertensive men, from 2.6 (2.0, 4.2) to 3.8 (2.5, 5.1) ms/mmHg (median (interquartile range)), and in control group, from 4.3 (2.7, 5.0) to 4.4 (3.1, 7.1) ms/mmHg. Instead, larger increase (p
