Cognitive and psychomotor responses to high-altitude exposure in sea level and high-altitude residents of Ecuador

Rats of various ages (2, 12, 24, and 40 mo of age) were exposed for 4 wk to either a simulated high altitude of 23,000 ft or to a Peoria, Ill., altitude of 650 ft above sea level. Hematocrit ratios, hemoglobin, and erythrocytic 2,3-diphospho-glycerate (2,3-DPG) concentrations were measured. Hematocrit and hemoglobin determinations revealed a decrease in erythrocytic content with increasing age, and the augmented erythropoietic response was seen in all age groups of animals as a result of altitude exposure. The maximal erythrocytic content of hemoglobin in the 40-mo-old animals was significantly lower than that of all other age groups. Erythrocytic 2,3-DPG levels were significantly changed by aging alone. In the 40-mo-old group there was a 35% increase over the next highest sea-level value. However, while erythrocytic 2,3-DPG content increased significantly in all other age groups following altitude exposure, it decreased 46% in the 40-mo-old group.

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Effects of baseline heart rate at sea level on cardiac responses to high-altitude exposure

The International Journal of Cardiovascular Imaging ◽

10.1007/s10554-020-01769-w ◽

2020 ◽

Vol 36 (5) ◽

pp. 799-810

Author(s):

Jingdu Tian ◽

Chuan Liu ◽

Yuanqi Yang ◽

Shiyong Yu ◽

Jie Yang ◽

...

Keyword(s):

Heart Rate ◽

High Altitude ◽

Sea Level ◽

Baseline Heart Rate ◽

Altitude Exposure ◽

Cardiac Responses

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Effects of high altitude and water deprivation on arginine vasopressin release in men

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00332.2003 ◽

2004 ◽

Vol 286 (1) ◽

pp. E20-E24 ◽

Cited By ~ 17

Author(s):

C. M. Maresh ◽

W. J. Kraemer ◽

D. A. Judelson ◽

J. L. VanHeest ◽

L. Trad ◽

...

Keyword(s):

High Altitude ◽

Sea Level ◽

Arginine Vasopressin ◽

Water Deprivation ◽

Urine Volume ◽

Plasma Osmolality ◽

Vasopressin Release ◽

Altitude Exposure ◽

Blood Pressures ◽

Healthy Males

High-altitude exposure changes the distribution of body water and electrolytes. Arginine vasopressin (AVP) may influence these alterations. The purpose of this study was to examine the effect of a 24-h water deprivation trial (WDT) on AVP release after differing altitude exposures. Seven healthy males (age 22 ± 1 yr, height 176 ± 2 cm, mass 75.3 ± 1.8 kg) completed three WDTs: at sea level (SL), after acute altitude exposure (2 days) to 4,300 m (AA), and after prolonged altitude exposure (20 days) to 4,300 m (PA). Body mass, standing and supine blood pressures, plasma osmolality (Posm), and plasma AVP (PAVP) were measured at 0, 12, 16, and 24 h of each WDT. Urine volume was measured at each void throughout testing. Baseline Posm increased from SL to altitude (SL 291.7 ± 0.8 mosmol/kgH2O, AA 299.6 ± 2.2 mosmol/kgH2O, PA 302.3 ± 1.5 mosmol/kgH2O, P < 0.05); however, baseline PAVP measurements were similar. Despite similar Posm values, the maximal PAVP response during the WDT (at 16 h) was greater at altitude than at SL (SL 1.7 ± 0.5 pg/ml, AA 6.4 ± 0.7 pg/ml, PA 8.7 ± 0.9 pg/ml, P < 0.05). In conclusion, hypoxia appeared to alter AVP regulation by raising the osmotic threshold and increasing AVP responsiveness above that threshold.

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Interleukin-6 response to exercise and high-altitude exposure: influence of α-adrenergic blockade

Journal of Applied Physiology ◽

10.1152/jappl.2001.91.5.2143 ◽

2001 ◽

Vol 91 (5) ◽

pp. 2143-2149 ◽

Cited By ~ 70

Author(s):

Robert S. Mazzeo ◽

Danielle Donovan ◽

Monika Fleshner ◽

Gail E. Butterfield ◽

Stacy Zamudio ◽

...

Keyword(s):

High Altitude ◽

Sea Level ◽

Interleukin 6 ◽

Moderate Intensity ◽

Adrenergic Blockade ◽

Moderate Intensity Exercise ◽

Exercise Tests ◽

Altitude Exposure ◽

Excretion Rates ◽

Response To Exercise

Interleukin-6 (IL-6), an important cytokine involved in a number of biological processes, is consistently elevated during periods of stress. The mechanisms responsible for the induction of IL-6 under these conditions remain uncertain. This study examined the effect of α-adrenergic blockade on the IL-6 response to acute and chronic high-altitude exposure in women both at rest and during exercise. Sixteen healthy, eumenorrheic women (aged 23.2 ± 1.4 yr) participated in the study. Subjects received either α-adrenergic blockade (prazosin, 3 mg/day) or a placebo in a double-blinded, randomized fashion. Subjects participated in submaximal exercise tests at sea level and on days 1 and 12 at altitude (4,300 m). Resting plasma and 24-h urine samples were collected throughout the duration of the study. At sea level, no differences were found at rest for plasma IL-6 between groups (1.5 ± 0.2 and 1.2 ± 0.3 pg/ml for placebo and blocked groups, respectively). On acute ascent to altitude, IL-6 levels increased significantly in both groups compared with sea-level values (57 and 84% for placebo and blocked groups, respectively). After 12 days of acclimatization, IL-6 levels remained elevated for placebo subjects; however, they returned to sea-level values in the blocked group. α-Adrenergic blockade significantly lowered the IL-6 response to exercise both at sea level (46%) and at altitude (42%) compared with placebo. A significant correlation ( P = 0.004) between resting IL-6 and urinary norepinephrine excretion rates was found over the course of time while at altitude. In conclusion, the results indicate a role for α-adrenergic regulation of the IL-6 response to the stress of both short-term moderate-intensity exercise and hypoxia.

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Arterial catecholamine responses during exercise with acute and chronic high-altitude exposure

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1991.261.4.e419 ◽

1991 ◽

Vol 261 (4) ◽

pp. E419-E424 ◽

Cited By ~ 35

Author(s):

R. S. Mazzeo ◽

P. R. Bender ◽

G. A. Brooks ◽

G. E. Butterfield ◽

B. M. Groves ◽

...

Keyword(s):

High Altitude ◽

Sea Level ◽

Neural Activity ◽

Chronic Exposure ◽

Physiological Responses ◽

Submaximal Exercise ◽

Altitude Exposure ◽

Acute And Chronic Exposure ◽

Over Time ◽

Catecholamine Levels

Exercise at high altitude is a stress that activates the sympathoadrenal systems, which could affect responses to acute altitude exposure and promote adaptations during chronic altitude exposure. However, catecholamine levels are not clearly described over time at high altitude. In seven male volunteers (23 yr, 72 kg), resting arterial norepinephrine concentrations (ng/ml) on arrival at Pikes Peak (0.338 +/- 0.041) decreased compared with sea-level values (0.525 +/- 0.034) but increased to above sea-level values after 21 days at 4,300 m (0.798 +/- 0.052). Furthermore, during 45 min of constant submaximal exercise, values were similar at sea level (1.670 +/- 0.221) and on acute exposure to 4,300 m (2.123 +/- 0.086) but increased after 21 days of chronic exposure (2.693 +/- 0.216). By contrast, resting arterial epinephrine values (ng/ml) during acute and chronic exposure (0.708 +/- 0.033 vs. 0.448 +/- 0.026) both exceeded those of sea level (0.356 +/- 0.020). During exercise values on arrival were greater than at sea level (0.921 +/- 0.024 vs. 0.397 +/- 0.035) but fell to 0.612 +/- 0.025 ng/ml after 21 days. Exercise norepinephrine levels were related to systemic vascular resistance measurements (r = 0.93), whereas epinephrine levels were related to circulating lactate (r = 0.95). We conclude that during exercise at altitude there is a dissociation between norepinephrine, an indicator of sympathetic neural activity, and epinephrine, an indicator of adrenal medullary response. These actions may account for different metabolic and physiological responses to acute vs. chronic altitude exposure.

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Aldosterone dynamics during graded exercise at sea level and high altitude

Journal of Applied Physiology ◽

10.1152/jappl.1975.39.1.18 ◽

1975 ◽

Vol 39 (1) ◽

pp. 18-22 ◽

Cited By ~ 49

Author(s):

J. T. Maher ◽

L. G. Jones ◽

L. H. Hartley ◽

G. H. Williams ◽

L. I. Rose

Keyword(s):

High Altitude ◽

Sea Level ◽

Renin Angiotensin System ◽

O2 Uptake ◽

Bicycle Exercise ◽

Hormonal Responses ◽

Angiotensin System ◽

Altitude Exposure ◽

Graded Exercise ◽

Low Altitude

Hormonal responses to graded exercise of eight low altitude residents were examined at sea level (SL) and after 1 (acute) and 11 (chronic) days at 4,300 m (HA). Caloric, water, and electrolyte intakes were controlled, as were temperature and humidity. Blood was sampled at rest and during light and moderate upright bicycle exercise (20 min at 40% and 75% of maximal O2 uptake, respectively). Mean VO2 max at HA was 27% lower than at SL. Resting plasma levels of aldosterone (Aldo), renin, and angiotensin II (A II) were significantly lower (P smaller than 0.05) on day 1 at HA compared to SL, but returned to SL values by day 11. Plasma cortisol values at rest were similar at SL and HA and were not significantly altered by light or moderate exercise. Renin, A II, and Aldo rose progressively with increasing workload in each environment. With acute HA, renin and Aldo were lower than at either SL or chronic HA. The chronic HA levels tended to approximate SL findings, implying adaptation. The data suggest that aldosterone is predominantly under the control of the renin-angiotensin system during graded exercise at sea level and that the response of this system is altered on acute high-altitude exposure.

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Coronary lipid deposition during chronic anemia or high altitude exposure

Journal of Applied Physiology ◽

10.1152/jappl.1961.16.1.103 ◽

1961 ◽

Vol 16 (1) ◽

pp. 103-106 ◽

Cited By ~ 15

Author(s):

Louis C. Fillios ◽

Stephen B. Andrus ◽

Chikayuki Naito

Keyword(s):

High Altitude ◽

Sea Level ◽

Prolonged Exposure ◽

Tissue Hypoxia ◽

Lipid Deposition ◽

High Altitudes ◽

Chronic Anemia ◽

Apparent Increase ◽

Altitude Exposure ◽

Per Se

Experimental anemia and polycythemia were studied in hypercholesteremic rats. The following results were noted: a) chronic anemia favors a significant increase in endocardial and coronary lipid deposition; b) rats made polycythemic by prolonged exposure to simulated high altitudes also had a marked degree of coronary involvement but no apparent increase in endocardial sudanophilia; whereas c) sea-level cobalt polycythemia does not appear to favor an increase in coronary or endocardial sudanophilia, suggesting that d) polycythemia, per se, does not favor an increase in lipid deposition at these sites. These findings suggest that tissue hypoxia may account for the above increases in coronary sudanophilia, while changes in endocardial sudanophilia appear to be related more closely to the circulating cholesterol for all the groups. Submitted on May 16, 1960

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Serum erythropoietin in humans at high altitude and its relation to plasma renin

Journal of Applied Physiology ◽

10.1152/jappl.1985.59.2.360 ◽

1985 ◽

Vol 59 (2) ◽

pp. 360-364 ◽

Cited By ~ 108

Author(s):

J. S. Milledge ◽

P. M. Cotes

Keyword(s):

Plasma Renin Activity ◽

High Altitude ◽

Sea Level ◽

Plasma Renin ◽

Western China ◽

Level Control ◽

Mount Everest ◽

Altitude Exposure ◽

Serum Erythropoietin ◽

Secondary Polycythemia

Serum immunoreactive erythropoietin (siEp) was estimated in samples collected from members of two scientific and mountaineering expeditions, to Mount Kongur in Western China and to Mount Everest in Nepal. SiEp was increased above sea-level control values 1 and 2 days after arrival at 3,500 m and remained high on ascent to 4,500 m. Thereafter, while subjects remained at or above 4,500 m, siEp declined, and by 22 days after the ascent to 4,500 m was at control values but increased on ascent to higher altitude. Thus siEp was at a normal level during the maintenance of secondary polycythemia from high-altitude exposure. On descent, with removal of altitude hypoxia, siEp decreased, but despite secondary polycythemia levels remained measurable and in the range found in subjects normally resident at sea level. On Mount Everest, siEp was significantly (P less than 0.01) elevated above preexpedition sea-level controls after 2–4 wk at or above 6,300 m. There was no correlation between estimates of siEp and plasma renin activity in samples collected before and during both expeditions.

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Oxidative stress and erythropoietin response in altitude exposure

Clinical & Investigative Medicine ◽

10.25011/cim.v31i6.4925 ◽

2008 ◽

Vol 31 (6) ◽

pp. 380 ◽

Cited By ~ 5

Author(s):

Hsien-Hao Huang ◽

Chih-Ly Han ◽

Horng-Chin Yan ◽

Woei-Yau Kao ◽

Chu-Dang Tsai ◽

...

Keyword(s):

Oxidative Stress ◽

High Altitude ◽

Sea Level ◽

Ferritin Level ◽

Acute Mountain Sickness ◽

Thiobarbituric Acid ◽

Altitude Exposure ◽

Delayed Recovery ◽

Mountain Sickness ◽

Stress Burden

Purpose: Oxidative stress and erythropoietin (EPO) levels are increased following high altitude exposure. We hypothesized that the altitude-oxidative stress and EPO response would be associated with the presence or absence of acute mountain sickness (AMS) in subjects exposed at high altitude. Methods: The study enrolled 29 healthy volunteers exposed at altitudes without strenuous physical exercise. Oxidative stress was determined by the spectrophotometric measurement of the colour occurring during the reaction of malondialdehyde (MDA) with thiobarbituric acid (TBA) on blood samples. Ferritin and EPO were also measured simultaneously. Results: During a rise in altitude at 2000 and 3000 m, there were no changes in plasma ferritin level in either of the 2 groups with or without AMS. In contrast, EPO increased at an altitude of 3000 m and after returning to sea level (28.2±2.7, 26.9±3.3 vs 12.2±1.4 and 17.1±1.6, P < 0.05, in group without AMS; 29.3±4.5, 22.8±2.7 vs 10.6±1.0 and 16.1±1.5, # P < 0.05, in group with AMS; compared with the baseline level and at the height of 2000 meters). At a height of 3000 m, plasma MDA level was elevated compared with that at the altitude of baseline and 2000 m in both groups of subjects with and without AMS (3.77±0.29 vs 1.14±0.17, and 1.64±0.22, P < 0.001, in subjects with AMS; 3.65±0.39 vs 1.71±0.21, and 1.73±0.21, P < 0.001, in subjects without AMS) . After returning to sea level, subjects without AMS had lower MDA oxidative stress compared with those with AMS (2.58±0.26 vs 3.51±0.24, P = 0.0223). Along with a rise in altitude, the oxidative stress in these both groups was not correlated with the changes in EPO (r2 = 0.0728, P = 0.1096). Conclusion: High altitude-induced oxidative stress, detected by MDA assay, is not different between the two groups of subjects with and without AMS. Upon return to sea level, subjects without AMS had lower MDA oxidative stress burden and higher EPO level than those with AMS. Whether the subjects with altitude illness had delayed recovery from oxidative stress merits further investigation.

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High-altitude is associated with better short-term survival in critically ill COVID-19 patients admitted to the ICU

10.1101/2021.01.22.21249811 ◽

2021 ◽

Author(s):

Pablo R. Morocho Jaramillo ◽

Katherine Simbaña-Rivera ◽

Javier V. Velastegui Silva ◽

Lenin Gómez-Barreno ◽

Ana B. Ventimilla Campoverde ◽

...

Keyword(s):

Clinical Outcome ◽

High Altitude ◽

Sea Level ◽

Critically Ill ◽

Clinical Laboratory ◽

Chronic Kidney Failure ◽

Disease Classification ◽

Term Survival ◽

Altitude Exposure ◽

Low Altitude

AbstractBackgroundThe novel human coronavirus, SARS-CoV-2, has affected at least 218 countries worldwide. Some geographical and environmental factors are positively associated with a better or worse prognosis concerning COVID-19 disease and with lower or higher SARS-CoV-2 transmission. High altitude exposure has been associated with lower SARS-CoV-2 attack rates; nevertheless, the role of chronic high-altitude exposure on the clinical outcome of critically ill COVID-19 patients has not been studied.ObjectiveTo compare the clinical course and outcomes of critically ill patients with COVID-19 hospitalized in two intensive care units (ICU) located at low and high altitude.Exposure and OutcomeTo explore the effect of two different elevations (10 m vs 2,850 m above sea level) on COVID-19 clinical outcome and survival.MethodsA prospective cohort, two-center study in confirmed COVID-19 adult patients admitted to a low altitude (Sea level) and high altitude (2,850 m) ICU units in Ecuador was conducted. Two hundred and thirty confirmed COVID-19 patients were enrolled from March 15th to July 15th, 2020. Sociodemographic, clinical, laboratory and imaging parameters including supportive therapies, pharmacological treatments and medical complications were reported and compared between the low and high-altitude groups.ResultsThe median age of all the patients was 60 years, 64.8% were men and 35.2% were women. A total of 105 (45.7%) patients had at least one underlying comorbidity, the most frequent being chronic diseases, such as hypertension (33.5%), diabetes (16.5%), and chronic kidney failure (5.7%). The APACHE II scale at 72 hours was especially higher in the low-altitude group with a median of 18 points (IQR: 9.5-24.0), compared to 9 points (IQR: 5.0-22.0) obtained in the group of high altitude. There is evidence of a difference in survival in favor of the high-altitude group (p = 0.006), the median survival being 39 days, compared to 21 days in the low altitude group.ConclusionThere has been a substantial improvement in survival amongst people admitted to the high-altitude critical care unit. High altitude living was associated with improved survival, especially among patients with no comorbidities. COVID-19 patients admitted to the high-altitude ICU unit have improved severity-of-disease classification system scores at 72 hours and reported better respiratory and ventilatory profiles than the low altitude group.

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