Sympathetic activity during passive heat stress in healthy aged humans
Gagnon D, Schlader ZJ, Crandall CG
The Journal of physiology · 50 citations
Review labels
Neutral facts our review recorded about how this study was done. They describe method, never whether we like the result.
How it was studied
- Design
- Controlled clinical trial (classified by our AI screen)
- Studied in
- People
- Main outcome
- Mechanisms only
Who paid for it
- Funding
- Independent funding
- Government
- National Heart, Lung, and Blood Institute
- Government
- NHLBI NIH HHS
- Grants
- National Heart, Lung, and Blood Institute (HL61388); National Heart, Lung, and Blood Institute (HL-84072)
Based on 2 listed funder(s).
Publication
- Published
- 2015-03-05 · J Physiol · vol. 593 · issue 9 · pp. 2225–2235
- Publisher
- Wiley
- Cited
- 58 citations · more than 93% of similar papers · 3.7× the field average
- Impact
- Top 10% most cited in its field
- References
- 44 works
- Access
- Open access (repository copy)
- Research areas
- Thermoregulation and physiological responses · Climate Change and Health Impacts · Infrared Thermography in Medicine
- Keywords
- Cold pressor test, Blood pressure, Medicine, Heat stress, Internal medicine, Sympathetic activity, Sympathetic nervous system, Heart rate, Catecholamine, Endocrinology, Animal science
- MeSH
- muscle, skeletal, sympathetic nervous system, humans, catecholamines, reflex, aging, adult, aged, female, male, hemodynamics, hot temperature, stress, physiological
3 authors
From US, BE
- Daniel GagnonTexas Health Dallas; Institute for Exercise and Environmental Medicine
- Zachary J. SchladerTexas Health Dallas; Nutrition Sciences (Belgium); Institute for Exercise and Environmental Medicine; University at Buffalo, State University of New York
- Craig G. Crandall · correspondingTexas Health Dallas; Institute for Exercise and Environmental Medicine
Abstract
Key points
Cardiovascular adjustments to heat stress are attenuated in healthy aged individuals, which could contribute to their greater prevalence of heat-related illnesses and deaths during heat waves. The attenuated cardiovascular adjustments in the aged could be due to lower increases in sympathetic nerve activity during heat stress. We examined muscle sympathetic nerve activity (MSNA) and plasma catecholamine concentrations in healthy young and aged individuals during whole-body passive heat stress. The main finding of this study is that increases in MSNA and plasma catecholamine concentrations did not differ between young and aged healthy individuals during passive heating. Furthermore, the increase in these variables did not differ when a cold pressor test and lower body negative pressure were superimposed upon heating. These findings suggest that attenuated cardiovascular adjustments to heat stress in healthy aged individuals are unlikely to be related to attenuated increases in sympathetic activity.
Abstract
Cardiovascular adjustments during heat stress are generally attenuated in healthy aged humans, which could be due to lower increases in sympathetic activity compared to the young. We compared muscle sympathetic nerve activity (MSNA) between 11 young (Y: 28 ± 4 years) and 10 aged (A: 70 ± 5 years) subjects prior to and during passive heating. Furthermore, MSNA responses were compared when a cold pressor test (CPT) and lower body negative pressure (LBNP) were superimposed upon heating. Baseline MSNA burst frequency (Y: 15 ± 4 vs. A: 31 ± 3 bursts min(-1) , P ≤ 0.01) and burst incidence (Y: 26 ± 8 vs. A: 50 ± 7 bursts (100 cardiac cycles (CC))(-1) , P ≤ 0.01) were greater in the aged. Heat stress increased core temperature to a similar extent in both groups (Y: +1.2 ± 0.1 vs. A: +1.2 ± 0.0°C, P = 0.99). Absolute levels of MSNA remained greater in the aged during heat stress (burst frequency: Y: 47 ± 6 vs. A: 63 ± 11 bursts min(-1) , P ≤ 0.01; burst incidence: Y: 48 ± 8 vs. A: 67 ± 9 bursts (100 CC)(-1) , P ≤ 0.01); however, the increase in both variables was similar between groups (both P ≥ 0.1). The CPT and LBNP further increased MSNA burst frequency and burst incidence, although the magnitude of increase was similar between groups (both P ≥ 0.07). These results suggest that increases in sympathetic activity during heat stress are not attenuated in healthy aged humans.
Abstract via Europe PMC. Copyright remains with the authors or publisher.
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