Oxygen consumption and body temperature in new‐born kittens subjected to hypoxia and reoxygenation

Moore, R. E.

doi:10.1113/jphysiol.1959.sp006357

Cited by 45 publications

(22 citation statements)

References 17 publications

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“…Alterations in SNS activity during hypoxic exposure may contribute to some of the physiological changes that accompany diminished oxygen supply. During acute hypoxic exposure, oxygen consumption and heat production fall (34)(35)(36) and hypothermia develops (34)(35)(36)(37)(38)(39)(40). This hypoxic depression of metabolism represents either the direct effect of oxygen lack at a cellular level, or the recruitment of a regulatory process that diminishes metabolic rate, or both (35).…”

Section: Discussionmentioning

confidence: 99%

Sympathoadrenal responses to acute and chronic hypoxia in the rat.

1983

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A B S T R A C T The sympathoadrenal responses to acute and chronic hypoxic exposure at 10.5 and 7.5% oxygen were determined in the rat. Cardiac norepinephrine (NE) turnover was used to assess sympathetic nervous system (SNS) activity, and urinary excretion of epinephrine (E) was measured as an index of adrenal medullary activity. The responses of the adrenal medulla and SNS were distinct and dependent upon the degree and duration of hypoxic exposure. Chronic hypoxia at 10.5% oxygen increased cardiac NE turnover by 130% after 3, 7, and 14 d of hypoxic exposure. Urinary excretion of NE was similarly increased over this time interval, while urinary E excretion was marginally elevated. In contrast, acute exposure to moderate hypoxia at 10.5% oxygen was not associated with an increase in SNS activity; in fact, decreased SNS activity was suggested by diminished cardiac NE turnover and urinary NE excretion over the first 12 h of hypoxic exposure, and by a rebound increase in NE turnover after reexposure to normal oxygen tension. Adrenal medullary activity, on the other hand, increased substantially during acute exposure to moderate hypoxia (2-fold increase in urinary E excretion) and severe hypoxia (>10-fold). In distinction to the lack of effect of acute hypoxic exposure (10.5% oxygen), the SNS was markedly stimulated during the first day of hypoxia exposure at 7.5% oxygen, an increase that was sustained throughout at least 7 d at 7.5% oxygen. These results demonstrate that chronic exposure to moderate and severe hypoxia increases the activity of the SNS and adrenal medulla, the effect being

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Section: Discussionmentioning

confidence: 99%

Sympathoadrenal responses to acute and chronic hypoxia in the rat.

1983

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“…Since the 1950s, this was known to occur in a broad range of small mammals (18) and in neonates of larger mammals, including humans (10,25). This hypoxia-induced drop in T b and metabolic depression serves a protective role by reducing O 2 demand, eliminating costly thermogenesis, improving blood O 2 affinity, and reducing the costs of ventilation (14,27,36,38,47,48).…”

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confidence: 99%

Ventilatory and metabolic responses to hypoxia in the smallest simian primate, the pygmy marmoset

Tattersall

Blank

Wood

2002

Journal of Applied Physiology

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Tattersall, Glenn J., James L. Blank, and Stephen C. Wood. Ventilatory and metabolic responses to hypoxia in the smallest simian primate, the pygmy marmoset. J Appl Physiol 92: 202-210, 2002; 10.1152/japplphysiol.00500.2001.-The pygmy marmoset (Cebuella pygmaea) is the smallest New World Monkey (average body mass of 120-130 g). As such, it faces possible challenges to thermoregulation. Small mammals (e.g., rats) are well known to lower body temperature and metabolism in response to hypoxia; however, small primates have not been studied in this respect nor have, in general, the interactions between metabolism and ventilation. Because little is known about these responses in small primates, it seemed of great interest to assess the hypoxiainduced metabolic depression and drop in body temperature and the associated ventilatory requirements in this species under hypoxic conditions. Exposure to graded hypoxia (30 min at each of 18, 16, 14, 12, and 10% O2) caused body temperature to drop from the normoxic value of 39 to 37°C. This was accompanied by a marked metabolic depression (O2 consumption was ϳ68% of the normoxic value, implying a suppression of metabolism greater than that predicted from a typical value of the effect of 10°C change on metabolism of 2-3 times). Minute ventilation declined in parallel to metabolism, maintaining a constant air-convection requirement during hypoxia; thus this species did not show the typical mammalian hyperventilation. Acute exposure to 10% O2 led to a similar overall decline in metabolism and body temperature and qualitative differences in the timing of these changes. The pygmy marmoset shares some similarities in its hypoxic metabolic response with other mammals of similar size yet appears to be unique in its much diminished ventilatory response to hypoxia. body temperature; thermoregulation; hypoxic ventilatory response; hypothermia; metabolic depression MANY ANIMALS RESPOND TO HYPOXIA by reducing body temperature (T b ) and metabolic rate (46). Since the 1950s, this was known to occur in a broad range of small mammals (18) and in neonates of larger mammals, including humans (10, 25). This hypoxia-induced drop in T b and metabolic depression serves a protective role by reducing O 2 demand, eliminating costly thermogenesis, improving blood O 2 affinity, and reducing the costs of ventilation (14,27,36,38,47,48). Furthermore, numerous studies support the conclusion that hypoxia resets the hypothalamic thermoregulatory set point to a lower level (9,(15)(16)(17)34), suggesting that this is a regulated process.Metabolism and thermoregulation affect ventilatory control (13, 30). Pulmonary ventilation is controlled so that O 2 delivery matches metabolic rate under varying states of metabolic demand (24). Thus breathing during hypoxic exposure is complicated by reduced metabolism and T b in small mammals. Lowered T b and metabolic rate decrease the metabolic drive to breathe (13), whereas hypoxia serves to increase the chemical drive to breathe. These drives for breathing conflict with o...

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“…According to several studies [5,7,9,12,17,29,45] severe prolonged hypoxia causes a drop of the body temperature in newborns.…”

Section: Resultsmentioning

confidence: 99%