Transfer of arachidonate from phosphatidylcholine to phosphatidylethanolamine and triacylglycerol in guinea pig alveolar macrophages
Guinea pig alveolar macrophages were labeled by incubation with either arachidonate or linoleate. Arachidonate labeled phosphatidylcholine (PC), phosphatidylethanolamine (PE) and triglycerides (TG) equally well, with each lipid containing about 30% of total cellular radioactivity. In comparison to arachidonate, linoleate was recovered significantly less in PE (7%) and more in TG (47%). To investigate whether redistributions of acyl chains among lipid classes took place, the macrophages were incubated with 1-acyl-2-(1-/sup 14/C)arachidonoyl PC or 1-acyl-2-(1-/sup 14/C)linoleoyl PC. After harvesting, the cells incubated with 1-acyl-2-(1-/sup 14/C)linoleoyl PC contained 86% of the recovered cellular radioactivity in PC, with only small amounts of label being transferred to PE and TG (3 and 6%, respectively). More extensive redistributions were observed with arachidonate-labeled PC. In this case, only 60% of cellular radioactivity was still associated with PC, while 22 and 12%, respectively, had been transferred to PE and TG. Arachidonate transfer from PC to PE was unaffected by an excess of free arachidonate which inhibited this transfer to TG for over 90%, indicating that different mechanisms or arachidonoyl CoA pools were involved in the transfer of arachidonate from PC to PE and TG. Cells prelabeled with 1-acyl-2-(1-/sup 14/C)arachidonoyl PC released /sup 14/C-label into the medium upon further incubation. This release was slightly stimulated by zymosan and threefold higher in the presence of the Ca2+-ionophore A23187. Labeling of macrophages with intact phospholipid molecules appears to be a suitable method for studying acyl chain redistribution and release reactions.
- Research Organization:
- State Univ. of Utrecht, The Netherlands
- OSTI ID:
- 6845628
- Journal Information:
- Lipids; (United States), Vol. 10
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ARACHIDONIC ACID
METABOLISM
MACROPHAGES
LABELLING
BIOCHEMICAL REACTION KINETICS
CARBON 14 COMPOUNDS
ENERGY TRANSFER
GUINEA PIGS
IN VITRO
LINOLEIC ACID
TRACER TECHNIQUES
TRIGLYCERIDES
ANIMAL CELLS
ANIMALS
CARBOXYLIC ACIDS
CONNECTIVE TISSUE CELLS
ESTERS
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
LIPIDS
MAMMALS
MONOCARBOXYLIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
PHAGOCYTES
REACTION KINETICS
RODENTS
SOMATIC CELLS
VERTEBRATES
550501* - Metabolism- Tracer Techniques