AJP - Lung Cellular and Molecular Physiology, Vol 269, Issue 2 209-L214, Copyright © 1995 by American Physiological Society
Surfactant treatment and ventilation effects on surfactant SP-A, SP-B, and SP-C mRNA levels in preterm lamb lungs
E. Woods, T. Ohashi, D. Polk, M. Ikegami, T. Ueda and A. H. Jobe
Department of Obstetrics and Gynecology, Harbor-University of California Los Angeles Medical Center, Torrance 90509, USA.
The effects of exogenous surfactant treatment combined with postnatal
ventilation on surfactant protein (SP)-A, SP-B, and SP-C steady-state mRNA
levels were evaluated in preterm sheep at 120, 132, and 139 days gestation.
Three groups were studied at each gestation period: animals ventilated and
treated with 100 mg/kg natural sheep surfactant, animals ventilated and not
treated with surfactant, and a comparison group of lambs that were neither
ventilated nor treated with surfactant. In unventilated lambs, SP-A and
SP-C mRNA levels measured by densitometry from Northern blots increased
between 120 and 132 days gestation (P < 0.05). At 120 days gestation, no
differences in SP-A, SP-B, or SP-C mRNA levels were noted among the three
groups. At 132 days gestation, SP-A mRNA levels increased in both
ventilated groups (P < 0.01), but no additional surfactant effect on
SP-A mRNA expression was detected. There were no changes in SP-B or SP-C
mRNA levels among the groups at 132 days gestation. At 139 days gestation,
mRNA levels for both SP-A and SP-B increased after ventilation, compared
with the unventilated groups (P < 0.05). Furthermore, an additional
effect of surfactant treatment to increase SP-A mRNA levels relative to
animals undergoing ventilation alone was noted (P < 0.05). We conclude
that postnatal changes in mRNA levels for the surfactant proteins are
gestationally regulated and protein specific.
