Details

Autor(en) / Beteiligte

• Schellenberg, Jean-Claude

Titel

Elastin and collagen in lungs of perinatal rats and fetal sheep

Ort / Verlag

ProQuest Dissertations & Theses

Erscheinungsjahr

1988

Quelle

ProQuest Dissertations & Theses A&I

Beschreibungen/Notizen

• The ontogeny of pulmonary elastin (desmosine) and collagen (hydroxyproline), their response to antenatal treatment with dexamethasone, and their role in the mechanical properties of the perinatal lung were studied. A radioimmunoassay for desmosine was developed. Rats were studied between Day 18 of gestation and postnatal Day 30 and sheep between Day 60 and term. Dexamethasone was administered on Day 17 to rats. Fetal sheep were infused at 124 days for 84 h with cortisol, triiodothyronine, prolactin or epidermal growth factor alone or in combination. Desmosine, hydroxyproline, and alveolar saturated phosphatidylcholine (SPC) of lungs which were distensible and stable (group 1) after the hormone treatment were compared with those of lungs that remained non-distensible and unstable (group 2). In rats, steep increases of desmosine concentration occurred between Day 20 and birth, and between postnatal Days 10 and 20. Hydroxyproline concentration doubled between Day 18 of gestation and birth, remained similar until postnatal Day 10, and doubled again by Day 30. In sheep, desmosine concentration increased 13-, 17-, 63- and 11-fold between Day 60 and term in non-dissected parenchyma, dissected (free from tubular structures of $>$0.1 mm diameter) parenchyma, pleura and trachea, respectively. A continuous sharp rise occurred after Day 110. Hydroxyproline concentation increased steadily 2.1-, 1.8-, 5- and 3-fold, respectively, in the four compartments. Dexamethasone in rats retarded lung growth between Day 18 and birth, body weight gain between birth and Day 15, and desmosine accumulation between postnatal Days 10 and 20. In sheep, concentrations of desmosine, hydroxyproline, and SPC were higher in lungs of group 1 than in group 2. Although quasi-static pressure-volume characteristics in group 1 were similar to term lungs, desmosine and hydroxyproline concentrations resembled those of 137 day old fetuses and concentrations of SPC were 6 times lower than at term. The main conclusions are: The time-course of desmosine accumulation in rats differs from that in sheep. Betamethasone induced pathological lung development in rats. The association of changes in the mechanical properties of the lungs with changes in elastin and collagen suggests that connective tissue plays a significant role in the functional maturation of the lung.