Altered lipid synthesis in type II pneumonocytes exposed to lung surfactant
Uptake of lung surfactant by isolated type II cells was accompanied by decreased incorporation of (/sup 3/H)choline, (/sup 14/C)-palmitate and (/sup 14/C)acetate into phospholipids. Inhibition of incorporation of radiolabeled precursors, like uptake of surfactant, was half-maximal at approximately 0.1 ..mu..mol surfactant lipid P/ml, and was not due to altered specific radioactivities of intracellular precursor pools. Activity of DHAP acyltransferase, but not G-3-P acyltransferase, was decreased in type II cells exposed to surfactant. This was reflected in a decreased /sup 14/C//sup 3/H ratio in total lipids synthesized when cells incubated with (U-/sup 14/C)glycerol and (2-/sup 3/H)glycerol were exposed to surfactant. Disaturated phosphatidylcholine, disaturated phosphatidylglycerol and cholesterol (individually or mixed) did not mimic the inhibition of precursor incorporation observed with whole surfactant. In contrast, an apoprotein fraction isolated from surfactant inhibited the incorporation of (/sup 3/H)choline into lipids by type II cells. Inhibitory activity of the apoprotein fraction (either alone or mixed with lipids) was half-maximal at approximately 0.5 ..mu..g protein/ml, and was labile to heat and to trypsin. Lipid synthesis in some other cell types (but not all) was also influenced by extracellular surfactant. These data support the proposition that synthesis of surfactant lipids is inhibited in type II cells that are taking up extracellular surfactant.
- Research Organization:
- Univ. of Texas Health Science Center, Dallas
- OSTI ID:
- 5271970
- Report Number(s):
- CONF-8606151-
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Vol. 45:6; ISSN FEPRA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
ACETATES
ALCOHOLS
AMINES
AMMONIUM COMPOUNDS
BIOLOGICAL EFFECTS
BODY
CARBON 14 COMPOUNDS
CARBOXYLIC ACID SALTS
CARBOXYLIC ACIDS
CHOLINE
DRUGS
ENZYME ACTIVITY
ENZYMES
ESTERS
GLYCEROL
HEXADECANOIC ACID
HYDROXY COMPOUNDS
ISOTOPE APPLICATIONS
ISOTOPE RATIO
LABELLED COMPOUNDS
LIPIDS
LIPOTROPIC FACTORS
LUNGS
MONOCARBOXYLIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
ORGANS
PHOSPHOLIPIDS
PRECURSOR
QUATERNARY COMPOUNDS
RESPIRATORY SYSTEM
SECRETION
SURFACTANTS
TRACER TECHNIQUES
TRANSFERASES
TRITIUM COMPOUNDS