| Popis: |
Timely, adequate production of pulmonary surfactant is critical for survival at birth. This process is dependent on both maternal nutrition and glucocorticoids. Fetal rat lung lipofibroblast triglyceride accumulation is saturable, temperature-dependent and stimulated by glucocorticoids and cyclic AMP in primary cell culture. Spontaneous triglyceride uptake by fibroblasts increases ninefold between 17 and 21 days (= term) gestation and is stimulated 30-80% by exogenous glucocorticoid treatment. Coculture of Type II cells with fibroblasts preloaded with 3H-trioleate and increasing amounts of triglyceride results in a concomitant increase in saturated phosphatidylcholine (SPC) synthesized by Type II cells. Dexamethasone stimulates mobilization of fibroblast triglyceride incorporation into Type II cell-SPC by 36-40%. The hormonally regulated uptake and mobilization of triglyceride suggest active recruitment of surfactant phospholipid substrate by both alveolar connective tissue and epithelial cells. |
