Calcium2S+-PS-dependent protein kinase C activity in fetal, neonate and adult rabbit lung and the release of surfactant-related material from isolated fetal rabbit type II alveolar cells

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Samuels, Emile Rasheed
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The fetal lung secretes significant quantities of surfactant during late gestation in preparation for respiration which must begin immediately after birth. Although initiation of surfactant synthesis/secretion may be accelerated, the underlying mechanisms of the process itself remain to be resolved. An important pathway in adult lung has implicated the a$\sp{2+}$-PS-dependent enzyme protein kinase C (PKC) in its regulation. The present study was undertaken to characterize the activity of Ca$\sp{2+}$-PS-dependent PKC in adult lung and to determine if PKC was involved in the processes of initiation of synthesis and secretion of surfactant-related compounds in fetal and neonate lung. Protein and phospholipid levels, and activity profiles of Ca$\sp{2+}$-PS-dependent PKC were determined from subcellular fractions of fetal, neonate and adult rabbit lung. The enzyme's activity in the lamellar body fraction from whole lung and isolated type II cells was examined in greater detail. Additionally, the effect of PKC activation on uptake and release of phosphotidylcholine precursors $\lbrack\sp{32}$P) and $\lbrack\sp3$H) choline by isolated fetal type II pneumocytes was observed using the PKC activator tetradecanoylphorbol acetate (TPA). (Abstract shortened by UMI.)