Response to Cooling Temperature in Infants  Born at an Altitude of 4,330 Meters

Frappell, Peter B.; León‐Velarde, Fabiola; Aguero, Lourdes; Mortola, Jacopo P.

doi:10.1164/ajrccm.158.6.9803071

Cited by 35 publications

(16 citation statements)

References 28 publications

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“…In human infants born at high altitude, acute cold exposure caused a thermogenic response significantly lower than in infants at sea level (11). This result could mean that the hypoxic gestation of the high-altitude infants depressed the developmental processes of their thermogenic mechanisms.…”

mentioning

confidence: 93%

Hypoxic incubation blunts the development of thermogenesis in chicken embryos and hatchlings

Azzam¹,

Szdzuy²,

Mortola³

2007

American Journal of Physiology-Regulatory, Integrative and Comp

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We asked to what extent sustained hypoxia during embryonic growth might interfere with the normal development of thermogenesis. White Leghorn chicken eggs were incubated at 38 degrees C either in normoxia (Nx, 21% O2) or in hypoxia [Hx, 15% O2, from embryonic day 5 (E5) until hatching]. The Hx embryos had lower body weight (W) throughout incubation, and hatching was delayed by about 10 h. For both groups, all measurements were conducted in normoxia. At embryonic day E11, the static temperature-oxygen consumption (ambient T-Vo2) curve was typically ectothermic (Q10 = 1.92-1.94) and similar between Nx and Hx. Toward the end of incubation (E20), the Q10 averaged 1.41 +/- 0.06 in Nx and 1.79 +/- 0.08 in Hx (P < 0.005), indicating that the onset of the thermogenic response in Hx lagged behind Nx. In the 1-day-old hatchlings (H1), body weight did not significantly differ between Nx and Hx. At H1, the T-Vo2 curves were endothermic-type, and more so in the older (>8 h old) than in the newly hatched (<8 h old) chicks, whether examined statically or dynamically as a function of time. In either case, the thermogenic responses of Hx were lower than those of Nx. In a 43-31 degrees C thermocline, the preferred T of the Hx hatchlings was around 37.3 degrees C, and similar to Nx, suggesting a similar setpoint for thermoregulation. We conclude that hypoxic incubation blunted the development of thermogenesis. This could be interpreted as an example of epigenetic regulation, in which an environmental perturbation during early development alters the phenotypic expression of a regulatory system.

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mentioning

confidence: 93%

Hypoxic incubation blunts the development of thermogenesis in chicken embryos and hatchlings

Azzam¹,

Szdzuy²,

Mortola³

2007

American Journal of Physiology-Regulatory, Integrative and Comp

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“…Under both conditions, infants at high altitude had slight, but significantly lower body and skin temperatures than their low altitude counterparts. At low altitude, cooling increased oxygen consumption by approximately 34%, but no significant increase occurred in the high altitude group (Frappell et al, 1998). Relative perinatal hypoxia may blunt the thermogenic capacity.…”

Section: Ventilation and Pulmonary Functionmentioning

confidence: 89%

Cardiopulmonary Transition in the High Altitude Infant

Niermeyer

2003

High Altitude Medicine & Biology

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The perinatal cardiopulmonary transition at high altitude differs from that at sea level because oxygen plays a fundamental role in the developmental changes from fetus to newborn infant. Under conditions of high altitude hypoxia, arterial oxygen saturations are lower, breathing patterns and maturation of respiratory control reflexes differ, and regression of fetal characteristics of the pulmonary vasculature proceeds more slowly. Several aspects of transition vary not only with postnatal age and altitude, but also with population group, suggesting an effect of genetic adaptation on perinatal physiology. Exposure to chronic high altitude hypoxia during the perinatal transition also results in apparent lifelong alterations in respiratory reflex responses and pulmonary vasoreactivity. Disruption of the normal process of cardiopulmonary transition can result in symptomatic high altitude pulmonary hypertension. The exaggerated hypoxemia associated with acute respiratory infections in young infants still undergoing transition contributes to infant mortality at high altitude.

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“…The characteristics of the two groups of infants are presented in Table 1. The large majority, albeit not all, of these infants were part of a study on neonatal thermogenic responses, the results of which have been presented elsewhere [16].…”

Section: Low Altitudementioning

confidence: 99%

“…Heart rate variability in high-altitude infants The infant, recently fed and wearing only a disposable napkin, was placed supine on a thin mattress into a humicrib, consisting of a stainless steel cylinder maintained at the desired temperature by a system of circulating water through coils of PVC tubing that surrounded the humicrib. Further details of the humicrib and its temperature control have been given elsewhere [16]. Ambient temperature, measured by two thermocouples on the inner wall of the humicrib, was set at 35 mC for 20 min (warm), followed by a further 20 min at 26 mC (cool).…”

Section: Measurementsmentioning

confidence: 99%

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Heart rate variability in 1-day-old infants born at 4330 m altitude

Mortola

León‐Velarde

AGUERO³

et al. 1999

Clinical Science

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In fetuses and newborn infants heart rate variability changes in conditions of acute and chronic hypoxia; we therefore asked whether heart rate variability of infants born at high altitude differed from that of low-altitude infants. Short-term recordings (4-5 min) of inter-beat intervals were obtained in 19 infants in Lima (50 m altitude) and in 15 infants in Cerro de Pasco (4330 m, barometric pressure approximately 450 mmHg, inspired oxygen pressure approximately 94 mmHg) during quiet rest in warm conditions (ambient temperature, Ta, approximately 35 degrees C). In 12 infants from each group recordings were also obtained during cooling (Ta approximately 26 degrees C). Heart rate variability was evaluated from 512 consecutive inter-beat intervals, with analysis based on time-domain and frequency-domain methods. At warm Ta, heart rate variability did not differ between the two groups. During cooling, heart rate increased only in the low-altitude group. As in the warm, during cooling most parameters of heart rate variability did not differ between the two groups. The only exception was the inter-beat interval power of the high-frequency range of the spectrum (0.15-0.4 Hz), which, at least in adults, is believed to be a reflection of vagal activity, and was greater in the high-altitude group. It is concluded that gestation at high altitude, despite its blunting effects on fetal growth, does not have a major impact on heart rate variability of the newborn. Nevertheless, the possibility that differences in response to cooling may reflect some limitation in heart rate control needs to be examined further.

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Response to Cooling Temperature in Infants Born at an Altitude of 4,330 Meters

Cited by 35 publications

References 28 publications

Hypoxic incubation blunts the development of thermogenesis in chicken embryos and hatchlings

Hypoxic incubation blunts the development of thermogenesis in chicken embryos and hatchlings

Cardiopulmonary Transition in the High Altitude Infant

Heart rate variability in 1-day-old infants born at 4330 m altitude

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