Uptake and release of arachidonic acid by platelets and cultured cells

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1985

OSTI ID:5531654

Neufeld, E J

The release by thrombin of arachidonic acid, and the accompanying phospholipid metabolism, were studied in human platelets. At 23/sup 0/C, arachidonate release was half-maximal by 10-30 sec after stimulation, and preceded substantial increase in phosphatidic acid (PA) mass. (/sup 3/H)-glycerol-labeled platelets synthesized phospholipids from (/sup 3/H) PA at a rate of 0.08-0.3 nmol/min/10/sup 9/ cells at 37/sup 0/C. This rate of PA turnover was not enhanced by thrombin stimulation. Thus, an increase in PA mass is not a necessary event in the pathway loading to arachidonate release, and the release of several nmol of arachidonate from PI in the first minute after thrombin stimulation could not have arisen via PA as an intermediate. Biological function of arachidonate-specific acyl-CoA synthetase was examined in platelets and in HSDM/sub 1/C/sub 1/ murine fibrosarcoma cells. Washed platelets were found to take up and esterify into cellular phospholipids eicosanoid precursor fatty acids present at concentrations of 5-500 nM. The uptake process was saturable with respect to fatty acid concentration, with apparent K/sub m/ less than or equal to 85 nM. Stearate, oleate and linoleate were taken up less rapidly, and with higher apparent K/sub m/'s (greater than or equal to 170 nM). High affinity uptake was also found in HSDM/sub 1/C/sub 1/ cells. The fatty acid structural requirements of arachidonoyl-CoA synthetase were examined. Among common mammalian fatty acids, only eicosanoid precursors and docosahexaenoate could serve as substrates. These studies strongly suggest that the synthetase is required for normal eicosanoid homeostasis.

• Research Organization: Washington Univ., St. Louis, MO (USA)
• OSTI ID: 5531654
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AFFINITY
ANIMALS
ARACHIDONIC ACID
BIOLOGICAL MATERIALS
BIOLOGICAL PATHWAYS
BLOOD
BLOOD CELLS
BLOOD PLATELETS
BODY FLUIDS
CARBOXYLIC ACIDS
CELL CULTURES
ENZYME ACTIVITY
ENZYMES
ESTERS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LIGASES
LIPIDS
MAMMALS
MAN
MATERIALS
METABOLISM
MONOCARBOXYLIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PHOSPHOLIPIDS
PRIMATES
SECRETION
TRACER TECHNIQUES
TRITIUM COMPOUNDS
UPTAKE
VERTEBRATES