Am. J. Respir. Crit. Care Med., Vol 149, No. 4, 04 1994, 1005-1011.
Fetal lung growth. Influence of pulmonary arterial flow and surgery in sheep
LD Wallen, SF Perry, JT Alston and JE Maloney
Department of Pediatrics, University of Calgary, Alberta, Canada.
Aberrant pulmonary arterial flow has been associated with pulmonary
hypoplasia, which is a common cause of death in newborns. The current
experiments were designed to confirm whether interruption of postductal
main pulmonary artery (MPA) flow causes pulmonary hypoplasia. In addition,
the effect of fetal surgery on lung growth was investigated. Fetal sheep,
instrumented at 107 to 115 d gestation (MPA ligated [n = 5], sham operated
[n = 3], and monitored [no thoracotomy, n = 5]), and unoperated twin
fetuses (140-d controls, n = 5) were used for analysis of lung growth at
136 to 140 d gestation. Morphometric measurement of lung tissue volumes and
assays of DNA, protein, and saturated phosphatidylcholine (SPC) were used
to assess lung growth. MPA ligation significantly decreased lung growth and
maturation as indicated by decreased surface area and volumes of fine
nonparenchyma, future airspace, and parenchymal tissue, and by decreased
lung weights, total DNA, protein, and SPC content. There was a significant
increase in the volume percentage of coarse nonparenchyma and a decrease in
the volume percentage of future airspace. The pattern of lung growth after
MPA ligation suggests that growth of peripheral airspace and parenchymal
tissue components does not occur, resulting in a significant decrease in
the amount of new tissue formed and delayed tissue maturation. Fetal
surgery significantly changed only DNA, protein, and SPC content. Studies
of the regulation of lung growth must consider the role of pulmonary
arterial flow and the smaller, but significant effects of fetal surgery.
