Hypothermia reduces cerebral metabolic rate and cerebral blood flow in newborn pigs

D. W. Busija, Charles Leffler

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Abstract

We examined effects of hypothermia on cerebral metabolic rate and cerebral blood flow in anesthetized, newborn pigs (1-4 days old). Cerebral blood flow (CBF) was determined with 15-μm radioactive microspheres. Regional CBF ranged from 44 to 66 ml·min-1·100 g-1, and cerebral metabolic rate was 1.94 ± 0.23 ml O2·100 g-1·min-1 during normothermia (39°C). Reduction of rectal temperature to 34-35°C decreased CBF and cerebral metabolic rate 40-50%. In another group of piglets, we examined responsiveness of the cerebral circulation to arterial hypercapnia during hypothermia. Although absolute values for the normocapnic and hypercapnic CBF were reduced by hypothermia and absolute values for normocapnic and hypercapnic cerebrovascular resistance were increased, the percentage changes from control in these variables during hypercapnia were similar during normothermia and hypothermia. In another group of animals that were maintained normothermic and exposed to two episodes of hypercapnia, there was no attenuation of cerebrovascular dilatation during the second episode. We conclude that hypothermia reduces CBF secondarily to a decrease in cerebral metabolic rate and that percent dilator responsiveness to arterial hypercapnia is unaltered when body temperature is reduced.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume253
Issue number4
StatePublished - 1987

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Cerebrovascular Circulation
Hypothermia
Swine
Hypercapnia
Regional Blood Flow
Body Temperature
Microspheres
Dilatation
Temperature

All Science Journal Classification (ASJC) codes

  • Physiology

Cite this

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title = "Hypothermia reduces cerebral metabolic rate and cerebral blood flow in newborn pigs",
abstract = "We examined effects of hypothermia on cerebral metabolic rate and cerebral blood flow in anesthetized, newborn pigs (1-4 days old). Cerebral blood flow (CBF) was determined with 15-μm radioactive microspheres. Regional CBF ranged from 44 to 66 ml·min-1·100 g-1, and cerebral metabolic rate was 1.94 ± 0.23 ml O2·100 g-1·min-1 during normothermia (39°C). Reduction of rectal temperature to 34-35°C decreased CBF and cerebral metabolic rate 40-50{\%}. In another group of piglets, we examined responsiveness of the cerebral circulation to arterial hypercapnia during hypothermia. Although absolute values for the normocapnic and hypercapnic CBF were reduced by hypothermia and absolute values for normocapnic and hypercapnic cerebrovascular resistance were increased, the percentage changes from control in these variables during hypercapnia were similar during normothermia and hypothermia. In another group of animals that were maintained normothermic and exposed to two episodes of hypercapnia, there was no attenuation of cerebrovascular dilatation during the second episode. We conclude that hypothermia reduces CBF secondarily to a decrease in cerebral metabolic rate and that percent dilator responsiveness to arterial hypercapnia is unaltered when body temperature is reduced.",
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AU - Busija, D. W.

AU - Leffler, Charles

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