Cardiovascular autonomic modulation and activity of carotid baroreceptors at altitude
Bernardi, Luciano, Passino, Claudio, Spadacini, Giammario, Calciati, Alessandro, Robergs, Robert A., Greene, Richard, Martignoni, Emilia, Anand, Inder, & Appenzeller, Otto (1998) Cardiovascular autonomic modulation and activity of carotid baroreceptors at altitude. Clinical Science, 95(5), pp. 565-573.
To assess the effects of acute exposure to high altitude on baroreceptor function in man we evaluated the effects of baroreceptor activation on R-R interval and blood pressure control at high altitude. We measured the low-frequency (LF) and high-frequency (HF) components in R-R, non-invasive blood pressure and skin blood flow, and the effect of baroreceptor modulation by 0.1-Hz sinusoidal neck suction. Ten healthy sea-level natives and three high-altitude native, long-term sea-level residents were evaluated at sea level, upon arrival at 4970 m and 1 week later.
Compared with sea level, acute high altitude decreased R-R and increased blood pressure in all subjects [sea-level natives: R-R from 1002 ± 45 to 775 ± 57 ms, systolic blood pressure from 130 ± 3 to 150 ± 8 mmHg; high-altitude natives: R-R from 809 ± 116 to 749 ± 47 ms, systolic blood pressure from 110 ± 12 to 125 ± 11 mmHg (P < 0.05 for all)]. One week later systolic blood pressure was similar to values at sea level in all subjects, whereas R-R remained elevated in sea-level natives. The low-frequency power in R-R and systolic blood pressure increased in sea-level natives [R-R-LF from 47 ± 8 to 65 ± 10% (P < 0.05), systolic blood pressure-LF from 1.7 ± 0.3 to 2.6 ± 0.4 In-mmHg2 (P < 0.05)], but not in high-altitude natives (R-R-LF from 32 ± 13 to 38 ± 19%, systolic blood pressure-LF from 1.9 ± 0.5 to 1.7 ± 0.8 In-mmHg2). The R-R-HF decreased in sea-level natives but not in high-altitude natives, and no changes occurred in systolic blood pressure-HF. These changes remained evident 1 week later. Skin blood flow variability and its spectral components decreased markedly at high altitude in sea-level natives but showed no changes in high-altitude natives. Neck suction significantly increased the R-R- and systolic blood pressure-LF in all subjects at both sea level and high altitude.
High altitude induces sympathetic activation in sea-level natives which is partially counteracted by active baroreflex. Despite long-term acclimatization at sea level, high-altitude natives also maintain active baroreflex at high altitude but with lower sympathetic activation, indicating a persisting high-altitude adaptation which may be genetic or due to baroreflex activity not completely lost by at least 1 year's sea-level residence.
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|Item Type:||Journal Article|
|Keywords:||adrenergic system; adult; aged; altitude; altitude acclimatization; article; autonomic nervous system; blood pressure regulation; cardiovascular system; carotid sinus pressoreceptor; controlled study; diastolic blood pressure; human; human experiment; nor, Adult; Aged; Altitude; Blood Pressure; Cardiovascular System; Carotid Sinus; Electrocardiography; Heart Rate; Humans; Microcirculation; Middle Aged; Pressoreceptors; Signal Processing, Computer-Assisted; Skin; Suction; Sympathetic Nervous System; Time Factors|
|Divisions:||Current > QUT Faculties and Divisions > Faculty of Health
Current > Schools > School of Exercise & Nutrition Sciences
|Deposited On:||21 Jul 2016 03:12|
|Last Modified:||21 Jul 2016 03:12|
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