Surfactant phospholipids and proteins are increased in fetal sheep with pulmonary hypertension secondary to fetal systemic arteriovenous fistula

Abstract

2004.-To determine whether prenatal surfactant storage was altered in a model of systemic arteriovenous fistula (SAVF) with pulmonary hypertension, a fistula was created between the internal jugular vein and the carotid artery in 120-day fetal lambs, and surfactant material was explored at 134 days. Total phospholipids (TPL) and disaturated phosphatidylcholine (DSPC) were increased in whole lung tissue. Phospholipid analysis of isolated lamellar body fraction evidenced a specific increase of surfactant pool size: TPL and DSPC in this fraction were enhanced 1.9 and 2.9 times, respectively, when referred to DNA. Although the steady-state level of transcripts of surfactant protein (SP)-A and SP-B was not found to be changed at the time of death, semiquantitative Western blot analysis revealed elevated SP-A and SP-B protein contents three-and twofold, respectively. These findings indicate markedly enhanced accumulation of surfactant material in the presence of surgically induced prenatal pulmonary hypertension. Although total lung cell number was increased by 26%, SP-B immunolabeling indicated that increased surfactant amount did not result from an increased alveolar type II cell proportion, but rather from an increased rate of storage. Whether similar changes in surfactant are encountered in human neonates with persistent pulmonary hypertension is worthy of investigation. fetus; lung surfactant; alveolar type II cells; disaturated phosphatidylcholine SYSTEMIC ARTERIOVENOUS FISTULA (SAVF) is a rare condition in the fetus that is known to be associated with persistent pulmonary hypertension (PPH) at birth. The newborn displays elevated pulmonary arterial pressure, abnormal pulmonary vascular reactivity, and high pulmonary vascular resistance leading to severe hypoxemia. Fetuses with vein of Galen arteriovenous malformation (14), highly vascularized sacrococcygeal teratoma, or chorioangioma are at risk of developing severe cardiac failure and PPH. To our knowledge, no studies have paid attention to the surfactant components in those neonates, probably because most of them were delivered prematurely due to severe heart failure and also because PPH is the primary concern. Because such studies can not readily be performed in humans, animal models of PPH may help in exploring surfactant material in this condition. Several experimental models of fetal pulmonary hypertension have been described over the past 15 years. Chronic intrauterine hypoxia (1), constriction (2), or ligation (31) of the ductus arteriosus induced pulmonary hypertension in the fetal lamb. In utero placement of aortopulmonary shunts in fetal lambs has also been shown to cause pulmonary hypertension at birth (34). More recently Jouannic et al. (27) have designed an experimental model of surgically created SAVF in the fetal lamb. They found that, at birth, there was an increase in pulmonary arterial pressure and resistance with no increase in pulmonary arterial blood flow (28). This was associated with striking structural remodeling of the pulmonary vascul...

Pulmonary effects of keratinocyte growth factor in newborn rats exposed to hyperoxia

“…Lipids were extracted from lung tissue homogenates (5-day-old pups) or from BAL fluid (7-dayold pups) using chloroform-methanol-water (1:2:0.8 vol/vol/vol). Individual phospholipids were separated by thin-layer chromatography, disaturated phosphatidylcholine (DSPC) was separated by osmium tetroxide and thin-layer chromatography, and then total phosphatidylcholine (PC), phosphatidylglycerol (PG), and DSPC spots revealed by iodine fixation were scrapped and mineralized, and phosphate was assayed as described previously (8).…”

“…Lung DNA was determined on the pellet of phospholipid extraction from lung tissue (5-day-old pups) by using the diphenylamine colorimetric method as described previously (8).…”