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Substrate utilization by the fetal sheep lung during the last trimester
1Department of Pediatrics, CVRI, University of California, San Francisco 94143.
Pediatric Research
|June 1, 1988
Summary
Fetal lung metabolism shifts near term, with increased oxygen use and amino nitrogen delivery, but decreased glucose uptake. These substrate changes may signal lung maturation.
Area of Science:
- Perinatal Physiology
- Fetal Development
- Respiratory Medicine
Background:
- In vivo substrate utilization in the developing fetal lung remains largely undescribed.
- Understanding fetal lung metabolism is crucial for assessing pulmonary maturation and potential complications.
Purpose of the Study:
- To investigate the in vivo pulmonary delivery and utilization of key substrates (oxygen, glucose, lactate, amino nitrogen) during late gestation in fetal lambs.
- To correlate substrate availability and utilization with fetal lung maturation.
Main Methods:
- Utilized chronically catheterized fetal lambs (119-141 days gestation).
- Measured substrate concentrations (oxygen, glucose, lactate, alpha-amino nitrogen) in pulmonary artery and vein.
- Determined lung blood flow using labeled microspheres.
Main Results:
- Lung oxygen availability and uptake increased significantly near term.
- Glucose availability and utilization decreased with advancing gestation.
- Amino nitrogen availability and delivery to the lung increased with fetal age.
- Lactate production by the lung remained constant, and the glucose/O2 ratio decreased, indicating a shift in substrate utilization.
Conclusions:
- Significant alterations in substrate delivery and utilization occur in the fetal lung near term.
- These metabolic shifts may act as signaling mechanisms for pulmonary maturation.
- A portion of fetal lung oxidative metabolism remains unaccounted for, suggesting other substrates are involved.