322 Formal Demonstration of Glucocorticoid-Dependent Fetal Lung SPC Synthesis

Abstract

Fetal lung explants develop the capacity to actively synthesize saturated phosphatidylcholine (SPC) in the presence of culture medium fortified with serum. The following criteria were set up to test whether this process is glucocorticoid(GC)-dependent: 1) GC must promote active SPC synthesis; 2) antiGC must inhibit active SPC synthesis; 3) in the absence of GC active SPC synthesis will not occur, but activity can be restored by adding GC. Day 19 fetal rabbit lung explants were cultured under the following conditions: Waymouth's medium and 10% fetal calf serum(FCS) or 10% stripped FCS(FCS-) plus cortisol(GC) or cortexolone (antiGC) for 9 days. SPC synthesis was quantified by measuring the rate of 3H-choline incorporated into 3H-SPC. Therefore 1)both serumGC(a) and cortisol (b) support active SPC synthesis; 2)serum GC is inhibited by antiGC(c);3)in the absence of GC(d) active SPC synthesis does not occur, but can be stimulated by cortisol(e). Therefore the fetal lung is dependent on GC for development of active SPC production. This study supported by NIH Grant #HL28315.