Cerebrovascular hypoxic and autoregulatory responses during reduced brain metabolism.

J. H. Donegan, R. J. Traystman, Raymond C Koehler, M. D. Jones, M. C. Rogers

Research output: Contribution to journalArticle

Abstract

The effect of reducing cerebral oxygen consumption (CMRO2) on the cerebral blood flow (CBF) responses to isocapnic hypoxic hypoxia and hypotension was examined in sheep. Newborn and adult animals were studied because of their different base-line CMRO2. Microsphere-measured CBF responses during pentobarbital coma (i.e., electroencephalographic silence) were compared with responses in conscious or lightly sedated animals. Induction of barbiturate coma reduced both CMRO2 and CBF by 50% from the awake value and by 25% from the value obtained in animals sedated with pentobarbital. The CBF response to 30 and 50% reductions in arterial O2 content (CaO2) was attenuated during coma, but only in proportion to the decrease in CMRO2. Whether CMRO2 was normal or reduced, the normoxic cerebral O2 delivery (CaO2 X CBF) was maintained during hypoxia in both newborns and adults. The relative autoregulatory index (fractional change in CBF divided by fractional change in perfusion pressure) was determined during graded hemorrhage. The index was not significantly different from zero (which represents perfect autoregulation) in awake, lightly sedated, or comatose animals. The data demonstrate that both base-line CBF and responses to hypoxia are closely tied to CMRO2 and that 50% reduction of CMRO2 does not impair cerebrovascular autoregulation.

Original languageEnglish (US)
JournalThe American journal of physiology
Volume249
Issue number2 Pt 2
StatePublished - Aug 1985

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Cerebrovascular Circulation
Coma
Brain
Pentobarbital
Homeostasis
Newborn Animals
Microspheres
Oxygen Consumption
Hypotension
Sheep
Perfusion
Hemorrhage
Pressure

ASJC Scopus subject areas

  • Medicine(all)

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Cerebrovascular hypoxic and autoregulatory responses during reduced brain metabolism. / Donegan, J. H.; Traystman, R. J.; Koehler, Raymond C; Jones, M. D.; Rogers, M. C.

In: The American journal of physiology, Vol. 249, No. 2 Pt 2, 08.1985.

Research output: Contribution to journalArticle

Donegan, J. H. ; Traystman, R. J. ; Koehler, Raymond C ; Jones, M. D. ; Rogers, M. C. / Cerebrovascular hypoxic and autoregulatory responses during reduced brain metabolism. In: The American journal of physiology. 1985 ; Vol. 249, No. 2 Pt 2.
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