Ventilatory Control at High Altitude

Weil, John V.

doi:10.1002/cphy.cp030221

Cited by 46 publications

(40 citation statements)

References 177 publications

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“…This pattern resembles the one seen in high altitude inhabitants (Sorensen & Severinghaus, 1968a;Santolaya, Lahiri, Alfaro & Schoene, 1989; see also Dempsey & Forster, 1982;Weil, 1986). The strategy seems to keep energy expenditure as low as possible.…”

Section: Discussionsupporting

confidence: 72%

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Ventilatory response to hyperoxia in newborn rats born in hypoxia‐‐possible relationship to carotid body dopamine.

Hertzberg

Hellström

Holgert

et al. 1992

The Journal of Physiology

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SUMMARY1. The influence of postnatal hypoxia on regulation of breathing and turnover rate of carotid body dopamine was examined in newborn rats. The percentage change in frequency, tidal volume and ventilation elicited by transient hyperoxia was assessed by flow plethysmography in unanaesthetized pups. The alteration in ventilation was taken as an index of peripheral chemoreceptor activity.2. The rats were born and reared in hypoxia. The inspired oxygen fraction (FI 0 ) was 0 12-0 14 until 2 days after delivery when the rats were placed into room air and the ventilatory chemoreflex was tested. At 4 days of age, i.e. 2 days after termination of hypoxia, the rats were tested again. The ventilatory data were compared with those from a previous study in normoxic rats. 3. We found a smaller decrease in ventilation (8-8+3-9%, mean+s.D.) in the hypoxic rats at 2 days of age compared with normoxic rats (22 7 + 6 4 %; P < 0001). In contrast, at 4 days of age there was no difference in ventilatory response between the posthypoxic rats (19 2 + 4-6 %) and normoxic pups (18 6 + 4 9 %).4. The turnover rates of dopamine in carotid bodies were determined at 0-6, 6-12, 12-24 h and 2 days after birth in hypoxia rats and in 2-day-old posthypoxic rat pups at different time intervals after termination of hypoxia. Postnatal hypoxia sustained a high turnover rate which decreased after termination of the hypoxia.5. We propose that the weak chemoreflex in hypoxic rat pups is brought about by a high release of carotid body dopamine.

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Section: Discussionsupporting

confidence: 72%

“…The mechanism for this is unknown, although an altered chemoreceptor function has been suspected (see e.g. Weil, 1986). The present findings may provide the link between prolonged hypoxia and a decreased chemoreceptor sensitivity.…”

Section: Discussionmentioning

confidence: 99%

Ventilatory response to hyperoxia in newborn rats born in hypoxia‐‐possible relationship to carotid body dopamine.

Hertzberg

Hellström

Holgert

et al. 1992

The Journal of Physiology

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“…Upon ascent to high altitude, ventilation increases (Boycott and Haldane, 1908;Barcroft, 1925;Haldane, 1927;Weil, 1986). This increase is a result of a complex interaction of partial pressures of gases and hydrogen ions on the peri heral chemoreceptor, the in the brain stem.…”

Section: Ventilationmentioning

confidence: 96%

“…This increase is a result of a complex interaction of partial pressures of gases and hydrogen ions on the peri heral chemoreceptor, the in the brain stem. Acute exposure to high altitude results in an immediate increase in ventilation which continues over the next 7 to 10 days at which point a plateau is reached (Weil, 1986); however, chronic exposure of years to atmospheric hypoxia results in a decrease in the ventilatory response both to hypoxia and exercise (Chiodi, 1957;Milledge and Lahiri, 1967;Severinghaus et al, 1966;Lahiri et al, 1969). These res owes are and raised at high altitude, but even longed exposure after maturity may resu t in a decreased ventilatory response to h oxia does appear to be, however, some variability in the blunting of this ventilatory response between hi h-altitude populations around ern Chile attain high levels o P exercise with a arable to or P ower than that achieved by Ewlanders demonstrate a marke !…”

Section: Ventilationmentioning

confidence: 98%

Increased diffusion capacity maintains arterial saturation during exercise in the Quechua Indians of Chilean Altiplano

Schoene

Roach

Lahiri

et al. 1990

American J Hum Biol

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The majority of Quechua Indians of the Altiplano of Northern Chile spend their lives between 3,500 and 4,500 meters, while some work as miners at much higher altitudes. In order to gain insight into the factors of 0, transfer in the lung that permit them to live and work in this hypoxic environment, we studied 20 male Quechuas (26.2 * 1.1 years) ofollaque, Chile, at 3,900 meters (barometric pressure = 490 torr). Resting pulmonary function and hypoxic ventilatory response (HVR) tests were done. Progressive exercise to exhaustion on a cycle ergometer was performed, and measurements of ventilation (VE, Umin, BTPS) oxygen consumption (V02, STPD), heart rate (bpm), steady-state diffusion capacity (DLCO, cddtorr), and hemoglobin (Hgb, gm/dl) were made. Vital capacities were 5.1 t 0.1 1 (BTPS) while DLCO's were 36.9 ? 2.6 cddtorr. Hemoglobin values were 18.3 ? 0.4 gm/dl. Isocapnic HVR' s were -0.17 2 0.05 (VE ltmid BTPS/SaO,, %), During steady-state exercise at 600 kpdmin subjects reached a V02 of 1.7 2 0.1 Urnin, aventilatory equivalent (VENO,) of33.2 IfI 1.02, aDLCO of 71.2 t 4.5 cddtorr with heart rates of 169.6 t 6.8 bpm, and an SaO, of 84.74 2 2.8%. At maximum exercise there was no subsequent arterial oxygen desaturation (SaO, = 87.0 t 1.0%) while VEN0,'s were increased to 44.5 2 3.4 with a VO, of 2.3 2 0.3 Urnin or 43.8 * 9.5 cc/kg/min. The ventilatory responses are similar to those of lowlanders exposed to comparable hypoxia during exercise (Schoene et al., Fed. Proc. 42:978,1983) but the DLCOs are significantly higher. We conclude that high-altitude natives of the Andes maintain arterial oxygen saturation during exercise because of an increased diffusion capacity for oxygen at the lung.Human populations who live at high altitude undergo a number of adaptations that allow them to survive in h poxic environments (Frisancho, 1975; Bager, 1978; Win-sion gradient for oxygen at each subsequent interphase. Furthermore, since survival depends on an adequate oxy en supply to the nisms must take place to compensate for the lower ambient oxygen partial ressure. A system which include: ventilation of air to and from the lungs, matching of that air with blood flow in the capillaries of the lungs, diffusion of oxygen from the gas to the blood phase, circulation of the blood by the heart tissues at all times, crucia B adaptive mechanumber of components make up t R is delivery and the vasculature to the body's tissues, diffusion of oxygen from the blood to the cell c oplasm, and the utilization of oxygen inThe topics of the development of body and lung growth at high altitude, the alterations in hem0 lobin and red blood cells, and the red blood cell production will be covered by other authors in this symposium. This paper will, therefore, concentrate primarily on the acute and chronic ventilatory responses to high altitude and diffusion of oxygen from the air to the blood during rest and exercise. It was the purpose of this study to compare these responses in the high altitude natives t T e mitochondria of the cell. rel...

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“…The possibility exists that the decrease in PI availability produced by hypoxia could be involved in the functional changes observed in the CB on chronic hypoxic exposure. For example, it is known that human and laboratory animal CBs become hyper-reactive to hypoxic stimuli on chronic hypoxic exposures (see [34]). It is also known that such hyper-reactivity is reflected in an increase in ventilation, action potential frequency in the sensory nerve of the CB and release of neurotransmitters by chemoreceptor cells [18,34].…”

Section: Discussionmentioning

confidence: 99%