| Popis: |
Differentiation-arrested and hormone-depleted monolayer cultures were developed from rat fetal lungs of 18-, 19-, 20-, and 22-days gestation. Incorporation of [3H]-choline into saturated phosphatidylcholine increased, whereas the rate of cell division decreased, with advancing gestational age. Both functions were modified by physiological concentrations of glucocorticoids, thyroid hormones, and insulin. Dexamethasone (0.055-5.5 nM) increased [3H]-choline incorporation into total saturated phosphatidylcholine in immature cultures only, but caused secretion in mature (day-22) cultures. Triiodothyronine (0.055-5.5 nM) increased [3H]-choline incorporation into total and secreted saturated phosphatidylcholine at all gestational ages. Insulin (5-50 microU/ml) inhibition of [3H]-choline incorporation into saturated phosphatidylcholine was evident only in mature cultures. Dexamethasone (0.55 nM), triiodothyronine (5.5 nM), and insulin (50 microU/ml) also had gestation-dependent effects on cell division. |
