Abstract
Introduction: We hypothesized that repeated respiratory straining maneuvers (repeated SM) designed to elevate arterial BPs (arterial baroreceptor loading) would acutely increase baroreflex responses. Methods: We tested this hypothesis by measuring cardiac baroreflex responses to carotid baroreceptor stimulation (neck pressures), and changes in heart rate and diastolic BP after reductions in BP induced by a 15-s Valsalva maneuver in 10 female and 10 male subjects at 1, 3, 6, and 24 h after performing repeated SM. Baroreflex responses were also measured in each subject at 1, 3, 6, and 24 h at the same time on a separate day without repeated SM (control) in a randomized, counter-balanced cross-over experimental design. Results: There was no statistical difference in carotid-cardiac and peripheral vascular baroreflex responses measured across time following repeated SM compared with the control condition. Integrated cardiac baroreflex response (ΔHR/ ASBP) measured during performance of a Valsalva maneuver was increased by approximately 50% to 1.1 ± 0.2 bpm · mm Hg-1 at 1 h and 1.0 ± 0.1 bpm · mm Hg-1 at 3 h following repeated SM compared with the control condition (0.7 ± 0.1 bpm · mm Hg-1 at both 1 and 3 h, respectively). However, integrated cardiac baroreflex response after repeated SM returned to control levels at 6 and 24 h after training. These responses did not differ between men and women. Conclusions: Our results are consistent with the notion that arterial baroreceptor loading induced by repeated SM increased aortic, but not carotid, cardiac baroreflex responses for as long as 3 h after repeated SM. We conclude that repeated SM increases cardiac baroreflex responsiveness which may provide patients, astronauts, and high-performance aircraft pilots with protection from development of orthostatic hypotension.
Original language | English (US) |
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Pages (from-to) | 212-219 |
Number of pages | 8 |
Journal | Aviation Space and Environmental Medicine |
Volume | 74 |
Issue number | 3 |
State | Published - Mar 1 2003 |
Keywords
- Baroreceptors
- Heart rate
- Valsalva maneuver
- Vasoconstriction
ASJC Scopus subject areas
- Public Health, Environmental and Occupational Health
- Pollution
- Medicine(all)