Hypoxic poikilothermia in rats.

Bhatia, B.; George, Susan; Rao, T V

doi:10.1152/jappl.1969.27.5.583

Cited by 34 publications

(4 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…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

View full text Add to dashboard Cite

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

show abstract

Section: Discussionmentioning

confidence: 99%

Sympathoadrenal responses to acute and chronic hypoxia in the rat.

1983

View full text Add to dashboard Cite

show abstract

“…The temperature in the chamber was maintained at 27+ J°C based on information provided by Folk (1969) that the lowest temperature at which the rat can maintain its body temperature at basal metabolic rate is 25 ° C. The report of Bhatia et al (1969) of a neutral temperature (dry bulb temperature) of 33 ° C for maintaining the set point in rat was also taken into consideration. The relative humidity within the chamber was about 50% and fresh air was allowed to flow into the chamber at the rate of 5.5 1/min.…”

Section: Methodsmentioning

confidence: 99%

Effect of intermittent chronic exposure to hypoxia on feeding behaviour of rats

Singh

Selvamurthy

1993

Int J Biometeorol

View full text Add to dashboard Cite

Healthy albino male rats were exposed to a simulated high altitude (HA) equivalent to 25,000 ft (7620 m) for 6 h daily, continuously for 21 days to study the feeding behaviour. The 24-h food and water intake and body weight once in 3 days were recorded. Blood samples were drawn once a week from the retro-orbital venous plexus for blood sugar analysis. All the parameters were recorded before, during and after exposure to simulated HA. The results show a decrease in 24-h food and water intake and decreased gain in body weight during hypoxic exposure, which showed a tendency to come back to control during the post-exposure period. The blood sugar reflected a state of mild hyperglycaemia during exposure to HA.

show abstract

“…6) and metabolism (10) during hypoxia. Over the intervening seven decades, a plethora of studies has been performed to test a variety of hypotheses to account for the mechanisms responsible for this hypoxic-induced hypothermia (1). Newborn mammals hyperventilate by reducing their metabolic rate, achieved by a regulated inhibition of all forms of thermogenesis (14).…”

mentioning

confidence: 99%

Ambient temperature modulates hypoxic-induced changes in rat body temperature and activity differentially

Bishop¹,

Silva²,

Krasney³

et al. 2001

American Journal of Physiology-Regulatory, Integrative and Comp

View full text Add to dashboard Cite

When rats, acclimated to an ambient temperature (T(a)) of 29 degrees C, are exposed to 10% O(2) for 63 h, the circadian rhythms of body temperature (T(b)) and level of activity (L(a)) are abolished, T(b) falls to a hypothermic nadir followed by a climb to a hyperthermic peak, L(a) remains depressed (Bishop B, Silva G, Krasney J, Salloum A, Roberts A, Nakano H, Shucard D, Rifkin D, and Farkas G. Am J Physiol Regulatory Integrative Comp Physiol 279: R1378-R1389, 2000), and overt brain pathology is detected (Krasney JA, Farkas G, Shucard DW, Salloum AC, Silva G, Roberts A, Rifkin D, Bishop B, and Rubio A. Soc Neurosci Abstr 25: 581, 1999). To determine the role of T(a) in these hypoxic-induced responses, T(b) and L(a) data were detected by telemetry every 15 min for 48 h on air, followed by 63 h on 10% O(2) from rats acclimated to 25 or 21 degrees C. Magnitudes and rates of decline in T(b) after onset of hypoxia were inversely proportional to T(a), whereas magnitudes and rates of T(b) climb after the hypothermic nadir were directly proportional to T(a). No hyperthermia, so prominent at 29 degrees C, occurred at 25 or 21 degrees C. The hypoxic depression of L(a) was least at 21 degrees C and persisted throughout the hypoxia. In contrast, T(a) was a strong determinant of the magnitudes and time courses of the initial fall and subsequent rise in T(b). We propose that the absence of hyperthermia at 21 and 25 degrees C as well as a persisting hypothermia may protect the brain from overt pathology.

show abstract

Hypoxic poikilothermia in rats.

Cited by 34 publications

References 0 publications

Sympathoadrenal responses to acute and chronic hypoxia in the rat.

Sympathoadrenal responses to acute and chronic hypoxia in the rat.

Effect of intermittent chronic exposure to hypoxia on feeding behaviour of rats

Ambient temperature modulates hypoxic-induced changes in rat body temperature and activity differentially

Contact Info

Product

Resources

About