Substrate utilization and kinetics of surfactant metabolism in evolving bronchopulmonary dysplasia.
OBJECTIVE
To use stable isotopically labeled precursors of pulmonary surfactant phospholipids to measure precursor utilization and surfactant turnover in premature infants who required mechanical ventilation at birth, 2 weeks, and >4 weeks of age.


METHODS
Infants of < or =28 weeks' gestation received simultaneous 24-hour intravenous infusions of [1,2,3,4-13C4] palmitate and [1-13C1] acetate at birth, 2 weeks, and > or =4 weeks of life. Disaturated phospholipids were extracted from sequential tracheal aspirate samples obtained over a period of 2 weeks. Fractional catabolic rate (a measure of total turnover) and the fractional synthetic rates from plasma palmitate and de novo synthesis (acetate) were measured.


RESULTS
The fractional catabolic rate increased from 25.3% +/- 7.0% per day at birth to 53.8% +/- 14.4% per day at 4 weeks (P=.001). The combined contribution from plasma palmitate and de novo synthesis to total synthesis increased from 44.2% +/- 19.8% at birth to 85.2% +/- 32.8% at 4 weeks (P=.03).


CONCLUSIONS
Total surfactant turnover increased in premature infants with evolving bronchopulmonary dysplasia. The increasing contributions from acetate and plasma palmitate suggest a decrease in surfactant phospholipid recycling.
Spence
Kimberly L
KL
Division of Newborn Medicine, the Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, and St. Louis Children's Hospital, St Louis, Missouri 63110, USA.
Zozobrado
James C
JC
Patterson
Bruce W
BW
Hamvas
Aaron
A
D019342:Acetic Acid / Q000378:metabolism*; D000367:Age Factors; D001997:Bronchopulmonary Dysplasia / Q000378:metabolism*; D002247:Carbon Isotopes; D005260:Female; D006801:Humans; D006819:Hyaline Membrane Disease / Q000378:metabolism*; D007223:Infant; D007231:Infant, Newborn; D007553:Isotope Labeling; D008297:Male; D019308:Palmitic Acid / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism; D037661:Pulmonary Surfactant-Associated Proteins / Q000378:metabolism*; D012720:Severity of Illness Index
D002247:Carbon Isotopes; D010743:Phospholipids; D037661:Pulmonary Surfactant-Associated Proteins; D019308:Palmitic Acid; D019342:Acetic Acid