Pulmonary gas exchange in andean natives at high altitude

Mithoefer, John C.; Remmers, John E.; Zubieta, G.; Mithoefer, M.C.

doi:10.1016/0034-5687(72)90097-7

Cited by 5 publications

(1 citation statement)

References 8 publications

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“…Dempsey and Wagner (1999) have suggested that exercise-induced arterial hypoxemia depends not only on an inadequate compensatory hyperventilation, but also on an excessive alveolar to arterial P O 2 difference. Unfortunately, evidence for a smaller alveolar to arterial P O 2 difference in the HA native includes contradictory evidence (Torrance et al, 1970(Torrance et al, /1971Mithoefer et al, 1972), but an increased breathing is indeed present in HA-SL subjects.…”

Section: Discussionmentioning

confidence: 93%

Ventilatory and Cardiovascular Responses to Hypoxia and Exercise in Andean Natives Living at Sea Level

Gamboa

León‐Velarde

Rivera-Ch

et al. 2001

High Altitude Medicine & Biology

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This study was designed to determine in subjects born at high altitude who move to sea level (HA-SL: born at 3500 m or above; n = 25) whether their cardiorespiratory responses to hypoxia and exercise are similar to those of sea level natives (SL,n = 25). The average age (39 +/- 7.3 yr), weight (72 +/- 7.3 kg), and height (1.71 +/- 0.01 m) did not differ between the SL and HA-SL subjects. All subjects were studied at rest or during exercise (60 W on cycle ergometer) while breathing room air (F(IO2) = 0.21 and P(B) = 760) or hypoxia (F(IO2) = 0.115 and PB = 760) in the following order: (1) normoxia at rest (NX-Rs), (2) hypoxia at rest (HX-Rs, 11.5% O(2)), hypoxia at exercise (HX-Ex), and normoxia at exercise (NX-Ex). Each period lasted 5 min. In absolute values, HA-SL showed significantly higher ventilation (V(E), L/min) during exercise in both normoxia and hypoxia and higher oxygen saturation (Sa(O2), %) during hypoxia both at rest and in exercise. They also had lower end-tidal CO(2) values (P(ETCO2), torr) at rest in both normoxia and hypoxia, but a higher P(ETCO2) in hypoxic exercise. Heart rate (HR, beats/min) was lower at rest in both normoxia and hypoxia, but higher in exercise. With acute hypoxia, Sa(O2) decreased less in the HA-SL than in the SL at rest (HA-SL, 9.2 +/- 0.8; SL, 12.0 +/- 0.82) and during exercise (HA-SL, 18.3 +/- 1.1; SL, 21.2 +/- 1.2). In conclusion, this study shows that HA-SL natives have increased ventilation and heart rate during exercise once their lifelong hypoxia is relieved.

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Section: Discussionmentioning

confidence: 93%

Ventilatory and Cardiovascular Responses to Hypoxia and Exercise in Andean Natives Living at Sea Level

Gamboa

León‐Velarde

Rivera-Ch

et al. 2001

High Altitude Medicine & Biology

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Exercise and Experiments of Nature

Joyner

Wiggins

Baker

et al. 2023

Comprehensive Physiology

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In this article, we highlight the contributions of passive experiments that address important exerciserelated questions in integrative physiology and medicine. Passive experiments differ from active experiments in that passive experiments involve limited or no active intervention to generate observations and test hypotheses. Experiments of nature and natural experiments are two types of passive experiments. Experiments of nature include research participants with rare genetic or acquired conditions that facilitate exploration of specific physiological mechanisms. In this way, experiments of nature are parallel to classical "knockout" animal models among human research participants. Natural experiments are gleaned from data sets that allow population-based questions to be addressed. An advantage of both types of passive experiments is that more extreme and/or prolonged exposures to physiological and behavioral stimuli are possible in humans. In this article, we discuss a number of key passive experiments that have generated foundational medical knowledge or mechanistic physiological insights related to exercise. Both natural experiments and experiments of nature will be essential to generate and test hypotheses about the limits of human adaptability to stressors like exercise.

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