Arterial Oxygenation Determines Autoregulation of Cerebral Blood Flow in the Fetal Lamb
作者:
W. TWEED,
J. COTE,
M. PASH,
H. LOU,
期刊:
Pediatric Research
(OVID Available online 1983)
卷期:
Volume 17,
issue 4, Part 1
页码: 246-249
ISSN:0031-3998
年代: 1983
出版商: OVID
数据来源: OVID
摘要:
We examined autoregulation of cerebral blood flow (CBF) over the range of oxygen tension commonly observed in the chronic fetal lamb preparation. Seventeen animals were surgically prepared under general anesthesia for chronicin uterostudies. Based on measured resting arterial Po2and calculated % saturation 24–48 h after surgery, two groups were defined: a normoxic group of eight with saturation of 57% or higher (our laboratory normal for physiologically stable preparations) and an hypoxic group of nine with saturation less than 57%. Regional CBF was measured with radiolabeled 15-μm microspheres. Autoregulation of CBF was assessed by measuring the change in CBF when fetal mean arterial blood pressure (MABP) was acutely decreased and increased by withdrawal and reinfusion of fetal blood. In normoxic animals CBF was constant over an MABP range of 42–61 torr in all four areas of the brain examined: cerebral hemispheres, basal ganglia, cerebellum, and brain stem. In hypoxic animals CBF was pressure dependent in all areas over an MABP range of 46–73 torr,i.e., autoregulation was abolished. These studies demonstrate that the mechanism of autoregulation is functionally developed in the mature fetal lamb, but operationally dependent upon arterial oxygen concentration. Below a saturation of approximately 50–60% CBF varies directly with perfusion pressure.
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