Ca/sup 2 +/-dependent and Ca/sup 2 +/-independent pathways for release of arachidonic acid from phosphatidylinositol in endothelial cells

Journal Article · Fri Sep 25 04:00:00 EDT 1987 · J. Biol. Chem.; (United States)

OSTI ID:5856940

Martin, T W; Wysolmerski, R B

The pathways for degradation of phosphatidylinositol (PI) were investigated in sonicated suspensions prepared from confluent cultures of bovine pulmonary artery endothelial cells. The time courses of formation of /sup 3/H-labeled and /sup 14/C-labeled metabolites of phosphatidyl-(/sup 3/H)inositol ((/sup 3/H)Ins-PI) and 1-stearoyl-2-(/sup 14/C) arachidonoyl-PI were determined at 37/sup 0/C and pH 7.5 in the presence of 2 mM EDTA with or without a 2 mM excess of Ca/sup 2 +/. The rates of formation of lysophosphatidyl-(/sup 3/H)inositol ((/sup 3/H)Ins-lyso-PI) and 1-lyso-2-(/sup 14/C) arachidonoyl-PI were similar in the presence and absence of Ca/sup 2 +/, and the absolute amounts of the two radiolabeled lyso-PI products formed were nearly identical. This indicated that lyso-PI was formed by phospholipase A1, and phospholipase A2 was not measurable. In the presence of EDTA, (/sup 14/C)arachidonic acid release from 1-stearoyl-2-(/sup 14/C)arachidonoyl-PI paralleled release of glycerophospho-(/sup 3/H)inositol ((/sup 3/H)GPI) from (/sup 3/H)Ins-PI. Formation of (/sup 3/H)GPI was inhibited by treatment with the specific sulfhydryl reagent, 2,2'-dithiodipyridine, and this was accompanied by an increase in (/sup 3/H)Ins-lyso-PI. In the presence of Ca/sup 2 +/, (/sup 14/C) arachidonic acid release from 1-stearoyl-2-(/sup 14/C)arachidonoyl-PI was increased 2-fold and was associated with Ca/sup 2 +/-dependent phospholipase C activity. Under these conditions, (/sup 3/H)inositol monophosphate production exceeded formation of (/sup 14/C)arachidonic acid-labeled phospholipase C products, diacylglycerol plus monoacylglycerol, by an amount that was equal to the amount of (/sup 14/C)arachidonic acid formed in excess of (/sup 3/H)GPI. Low concentrations of phenylmethanesulfonyl fluoride (15-125 microM) inhibited Ca/sup 2 +/-dependent (/sup 14/C)arachidonic acid release, and the decrease in (/sup 14/C) arachidonic acid formed was matched by an equivalent increase in /sup 14/C label in diacylglycerol plus monoacyclglycerol.

• Research Organization: St. Louis Univ. School of Medicine, MO
• OSTI ID: 5856940
• Journal Information: J. Biol. Chem.; (United States), Journal Name: J. Biol. Chem.; (United States) Vol. 262:27; ISSN JBCHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALKALINE EARTH METAL COMPOUNDS
ANIMAL TISSUES
ANIMALS
ARACHIDONIC ACID
ARTERIES
BIOLOGICAL PATHWAYS
BLOOD VESSELS
BODY
CALCIUM COMPOUNDS
CARBON 14 COMPOUNDS
CARBOXYLESTERASES
CARBOXYLIC ACIDS
CARDIOVASCULAR SYSTEM
CATIONS
CATTLE
CELL CULTURES
CHARGED PARTICLES
DOMESTIC ANIMALS
ENDOTHELIUM
ENZYME ACTIVITY
ENZYMES
ESTERASES
ESTERS
HYDROLASES
INHIBITION
IONS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LIPASE
LIPIDS
MAMMALS
METABOLISM
MONOCARBOXYLIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
ORGANS
PHOSPHOLIPIDS
RUMINANTS
SECRETION
TISSUES
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES