Tolerance of cold-acclimated and unacclimated rats to hypoxia at 1.7�C

Altland, Paul D.; Highman, Benjamin; Sellner, R. G.; Parker, Megan N.; Brubach, H. F.

doi:10.1007/bf01553646

Cited by 6 publications

(4 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The results of the present study support the work of LeBlanc (1969) with rodents, and extend it to human participants. However, these experimental results are in contrast to the findings of Fregly (1953, 1954) and Altland et al (1973) who exposed rodents to prolonged moderately cold air exposures before the addition of a hypoxic environment. A similar cross‐sensitisation response to restraint stress was also described in rats that were exposed to intermittent hypoxia (Ma et al 2008).…”

Section: Discussioncontrasting

confidence: 83%

“…A similar cross‐sensitisation response to restraint stress was also described in rats that were exposed to intermittent hypoxia (Ma et al 2008). The effects reported during hypoxic exposures by Fregly (1953, 1954) and Altland et al (1973) may be the result of a specific metabolic habituation to the cold, which increases oxygen consumption to defend internal body temperature. In an oxygen depleted environment, the increased metabolic rate results in the rats’ reduced tolerance.…”

Section: Discussionmentioning

confidence: 99%

“…Groups of rats that were not habituated to short cold exposures or lived in consistently cool environments did not demonstrate an improved response to hypoxic conditions. Others have also reported that prolonged moderately cold conditions had no effect (Fregly, 1954) or a detrimental effect on responses to hypoxia (Fregly, 1953; Altland et al 1972, 1973).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

‘Cross-adaptation’: habituation to short repeated cold-water immersions affects the response to acute hypoxia in humans

Lunt

Barwood

Corbett

et al. 2010

The Journal of Physiology

View full text Add to dashboard Cite

Adaptation to an environmental stressor is usually studied in isolation, yet these stressors are often encountered in combination in the field, an example being cold and hypoxia at altitude. There has been a paucity of research in this area, although work with rodents indicates that habituation to repeated short cold exposures has a cross-adaptive effect during hypoxia. The present study tested the hypothesis that cross-adaptation is also possible with humans. Thirty-two male volunteers were exposed to 10 min bouts of normoxic and hypoxic (F IO 2 0.12) rest and exercise (100 W on a recumbent cycle ergometer). These were repeated after a 96 h interval, during which participants completed six, 5 min immersions in either cold (12• C, CW) or thermoneutral water (35• C, TW). Venous blood samples were taken immediately after each bout, for determination of catecholamine concentrations. A three-lead ECG was recorded throughout and the final 5 min of each bout was analysed for heart rate variability using fast fourier transformations (and displayed as log transformed data (ln)). In comparison with the first hypoxic exercise exposure, the second exposure of the CW group resulted in an increased ln high frequency (ln HF) power (P < 0.001) and reduced adrenaline (P < 0.001) and noradrenaline concentrations (P < 0.001). Adrenaline and noradrenaline concentrations were lower in the CW group during the second hypoxic exercise compared to the TW group (P = 0.042 and P = 0.003), but ln HF was not. When separated into hypoxic sensitive and hypoxic insensitive subgroups, ln HF was higher in the hypoxic sensitive CW group during the second hypoxic exercise than in any of the other subgroups. Cold habituation reduced the sympathetic response (indicated by the reduced catecholamine concentrations) and elevated the parasympathetic activity (increased ln HF power) to hypoxic exercise. These data suggest a generic autonomic cross-adaptive effect between cold habituation and exposure to acute hypoxia in humans. Abbreviations CW, cold water; HRV, heart rate variability; TW, thermoneutral water.

show abstract

Section: Discussioncontrasting

confidence: 83%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

‘Cross-adaptation’: habituation to short repeated cold-water immersions affects the response to acute hypoxia in humans

Lunt

Barwood

Corbett

et al. 2010

The Journal of Physiology

View full text Add to dashboard Cite

show abstract

“…No beneficial or detrimental effects of hypoxic exposure (novel stressor) to cold adapted animals have been related to specific metabolic habituation to cold. In cold adapted animals, the increase in O 2 consumption (to keep the body temperature normal) is responsible for reduced tolerance in response to hypoxic exposure [2,54,55]. Stress sensitization is opposite to stress adaptation, in which the prior exposure of stress sensitizes the individual and subsequently, stress response is higher in response to subsequent stress exposures.…”

Section: Discussionmentioning

confidence: 98%