In vivo labeling of brain phospholipids by long-chain fatty acids: relation to turnover and function.
An experimental method and model are described to quantitate kinetics of in vivo incorporation of fatty acids (FA) into stable brain phospholipids. When a radiolabeled long-chain FA is injected intravenously in a rat, it rapidly equilibrates with brain FA-CoA, the precursor pool for phospholipids. As different labeled FA enter different sn positions of specific phospholipids, a combination of labels can be used to investigate roles of different phospholipids in brain function and structure. By taking into account dilution lambda of specific activity of brain FA-CoA, compared with specific activity of FA in plasma, half-lives of FA in individual brain phospholipids can be calculated. Values for lambda less than 0.02 suggest marked recycling, and give half-lives two orders of magnitude smaller than literature values. A half-life of arachidonate in phosphatidylinositol of 0.66 h (turnover = 105%h) is consistent with active participation of this FA in phospholipase A2 mediated signal transduction.
Rapoport
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Laboratory of Neurosciences, National Institute on Aging, National Institutes of Health, Bethesda, Maryland 20892, USA.
D000818:Animals; D001115:Arecoline / Q000494:pharmacology; D001921:Brain / Q000378:metabolism*; D002250:Carbon Radioisotopes; D005227:Fatty Acids / Q000378:metabolism*; D006207:Half-Life; D007700:Kinetics; D015394:Molecular Structure; D010743:Phospholipids / Q000378:metabolism*; D051381:Rats; D014316:Tritium
D002250:Carbon Radioisotopes; D005227:Fatty Acids; D010743:Phospholipids; D014316:Tritium; D001115:Arecoline