Platelet-activating factor stimulates metabolism of phosphoinositides via phospholipase A2 in primary cultured rat hepatocytes

Journal Article · Wed Jul 01 00:00:00 EDT 1987 · J. Lipid Res.; (United States)

OSTI ID:6089997

Okayasu, T; Hasegawa, K; Ishibashi, T

Addition of platelet-activating factor (PAF) to cells doubly labeled with (/sup 14/C)glycerol plus (/sup 3/H)arachidonic acid resulted in a transient decrease of (/sup 14/C)glycerol-labeled phosphatidylinositol (PI) and a transient increase of (/sup 14/C)glycerol-labeled lysophosphatidylinositol (LPI). (/sup 3/H)Arachidonate-labeled PI, on the other hand, decreased in a time-dependent manner. The radioactivity in phosphatidylethanolamine, phosphatidylcholine, sphingomyelin, and phosphatidylserine did not change significantly. The /sup 3/H//sup 14/C ratio decreased in PI in a time-dependent manner, suggesting the involvement of a phospholipase A2 activity. Although PAF also induced a gradual increase of diacylglycerol (DG), the increase of (/sup 14/C)glycerol-labeled DG paralleled the loss of triacyl (/sup 14/C)glycerol and the /sup 3/H//sup 14/C ratio of DG was 16 times smaller than that of PI. Thus, DG seemed not to be derived from PI. In myo- (/sup 3/H)inositol-prelabeled cells, PAF induced a transient decrease of (/sup 3/H)phosphatidylinositol-4,5-bis-phosphate (TPI) and (/sup 3/H)phosphatidylinositol-4-phosphate (DPI) at 1 min. PAF stimulation of cultured hepatocytes prelabeled with /sup 32/Pi induced a transient decrease of (/sup 32/P)polyphosphoinositides at 20 sec to 1 min. (/sup 32/P)LPI appeared within 10 sec after stimulation and paralleled the loss of (/sup 32/P)PI. (/sup 3/H)Inositol triphosphate, (/sup 3/H)inositol diphosphate, and (/sup 3/H)inositol phosphate, which increased in a time-dependent manner upon stimulation with adrenaline, did not accumulate with the stimulation due to PAF. These observations indicate that PAF causes degradation of inositol phospholipids via phospholipase A2 and induces a subsequent resynthesis of these phospholipids.

• Research Organization: Hokkaido Univ. School of Medicine, Sapporo, Japan
• OSTI ID: 6089997
• Journal Information: J. Lipid Res.; (United States), Vol. 28:7
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
BLOOD COAGULATION FACTORS
BIOLOGICAL FUNCTIONS
CARBON 14 COMPOUNDS
QUANTITY RATIO
LIPASE
ENZYME ACTIVITY
PHOSPHOLIPIDS
METABOLISM
TRITIUM COMPOUNDS
ARACHIDONIC ACID
CELL CULTURES
GLYCEROL
INOSITOL
LIVER CELLS
PHOSPHATES
PHOSPHORUS 32
RATS
TIME DEPENDENCE
TRACER TECHNIQUES
ALCOHOLS
ANIMAL CELLS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBOHYDRATES
CARBOXYLESTERASES
CARBOXYLIC ACIDS
COAGULANTS
DAYS LIVING RADIOISOTOPES
DRUGS
ENZYMES
ESTERASES
ESTERS
FUNCTIONS
HEMATOLOGIC AGENTS
HYDROLASES
HYDROXY COMPOUNDS
INOSITOLS
ISOTOPE APPLICATIONS
ISOTOPES
LABELLED COMPOUNDS
LIGHT NUCLEI
LIPIDS
MAMMALS
MONOCARBOXYLIC ACIDS
MONOSACCHARIDES
NUCLEI
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
OXYGEN COMPOUNDS
PHOSPHORUS COMPOUNDS
PHOSPHORUS ISOTOPES
RADIOISOTOPES
RODENTS
SACCHARIDES
SOMATIC CELLS
VERTEBRATES
550501* - Metabolism- Tracer Techniques