Fetal cerebral responses to ventilation and oxygenation in utero

Journal Article · Thu Dec 01 00:00:00 EST 1988 · American Journal of Physiology; (USA)

OSTI ID:6036836

Gleason, C A; Jones, Jr, M D; Traystman, R J; Notter, R H ^[1]

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1. Johns Hopkins Univ. School of Medicine, Baltimore, MD (USA) Univ. of Rochester School of Medicine and Dentistry, NY (USA)

Previous studies have shown that cerebral oxygen consumption (CMRO{sub 2}) increases by nearly 50% at birth. The perinatal factors responsible for this increase are unknown; however, one possibility is that fetal CMRO{sub 2} is constrained by the normal intrauterine arterial Po{sub 2} (Pa{sub 0{sub 2}}) of {approximately}20 mmHg. The authors investigated this possibility in seven near-term chronically instrumented fetal sheep (131-138 days gestation) in which they inserted vascular catheters and an endotracheal tube. After 1-3 days recovery, they measured cerebral blood flow (CBF) with radiolabeled microspheres and calculated CMRO{sub 2}. Measurements were made in utero under three conditions for each fetus: (1) nonventilated control; (2) ventilation with 3% O{sub 2}-5% CO{sub 2}-92% N{sub 2}; and (3) ventilation with an inspired oxygen concentration sufficient to raise fetal Pa{sub 0{sub 2}} to normal newborn levels. The results showed that increasing fetal arterial Po{sub 2} to postnatal levels did not consistently increase CMRO{sub 2}. CBF decreased as arterial O{sub 2} content (Ca{sub 0{sub 2}}) rose, with an inverse hyperbolic response similar to that previously found to relate CBF to Ca{sub 0{sub 2}} during fetal hypoxic hypoxia. This indicates that the normally low intrauterine Pa{sub 0{sub 2}} does not intrinsically limit CMRO{sub 2} and implies that the rapid increase in CMRO{sub 2} at birth reflects the activation of specific cellular and physiological processes at (or near) this unique developmental event.

• OSTI ID: 6036836
• Journal Information: American Journal of Physiology; (USA), Vol. 255:6; ISSN 0002-9513
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
CEREBRUM
BLOOD FLOW
FETUSES
VENTILATION
OXYGEN
METABOLISM
BLOOD PRESSURE
GADOLINIUM 153
GLUCOSE
INDIUM 114
LACTIC ACID
MICROSPHERES
NIOBIUM 95
PH VALUE
RUTHENIUM 103
SCANDIUM 46
TIN 113
ALDEHYDES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
BODY
BRAIN
CARBOHYDRATES
CARBOXYLIC ACIDS
CENTRAL NERVOUS SYSTEM
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
ELEMENTS
EVEN-ODD NUCLEI
GADOLINIUM ISOTOPES
HEXOSES
HYDROXY ACIDS
INDIUM ISOTOPES
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
ISOMERIC
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
MINUTES LIVING RADIOISOTOPES
MONOSACCHARIDES
NERVOUS SYSTEM
NIOBIUM ISOTOPES
NONMETALS
NUCLEI
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
RADIOISOTOPES
RARE EARTH ISOTOPES
RARE EARTH NUCLEI
RUTHENIUM ISOTOPES
SACCHARIDES
SCANDIUM ISOTOPES
SECONDS LIVING RADIOISO
TIN ISOTOPES
551001* - Physiological Systems- Tracer Techniques