title: Variation in human erythrocyte membrane unsaturated Fatty acids: correlation with cardiovascular disease.
abstract: BACKGROUND
  Whether cell membrane fatty acid (FA) composition is a useful indicator of vascular disease is unclear.
  
  
  OBJECTIVE
  To study variation of erythrocyte (RBC) membrane FA in samples from healthy volunteers, hospitalized patients, and cardiac troponin I-elevated patients with myocardial damage without a priori assumptions as to FA composition.
  
  
  METHODS
  We separated FAs extracted from RBCs by gas chromatography and identified them by mass spectrometry. Fatty acids with abundance greater than 1% of total were quantified and compared: hexadecanoic (C16:0), octadecadienoic (C18:2), cis- and trans-octadecenoic (C18:1), and eicosatetraenoic (C20:4) acids. Deuterated standards established proportionality of FA recovery. The cis- and trans-C18:1 identification was verified by comparison with standards.
  
  
  RESULTS
  In troponin-positive samples, C18:2 to C18:1 ratios were increased 30% compared with healthy controls or with random patient samples. Erythrocyte trans-C18:1 had a wide variation, approximately 10-fold, in all groups but without differences between groups. Replicates showed that the wide range of RBC trans-FA load is not due to analytic variation. In healthy subjects, the RBC content of lower- molecular weight FAs (C16-C18) correlated with serum low-density lipoprotein cholesterol, but despite the established relationship between dietary trans-FA and increased low-density lipoprotein cholesterol, lipid profiles had no correlation with RBC trans-FA content.
  
  
  CONCLUSIONS
  Erythrocyte accumulation of unsaturated FA may be a useful indicator of vascular disease, whereas the wide range in trans-FAs suggests that both diet and genetic variation affect RBC trans-FA accumulation. Unsaturated FAs increase membrane fluidity and may reflect a natural response to subclinical vascular changes, which may in turn reflect increased risk of clinical disease.
authors.affiliation: Department of Pathology & Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA.
authors.forename: Jorge L
authors.initials: JL
authors.lastname: Sepulveda
authors.forename: Yvette C
authors.initials: YC
authors.lastname: Tanhehco
authors.forename: Monica
authors.initials: M
authors.lastname: Frey
authors.forename: Lida
authors.initials: L
authors.lastname: Guo
authors.forename: Lorna J
authors.initials: LJ
authors.lastname: Cropcho
authors.forename: K Michael
authors.initials: KM
authors.lastname: Gibson
authors.forename: Harry C
authors.initials: HC
authors.lastname: Blair
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D002318:Cardiovascular Diseases / Q000097:blood* / Q000453:epidemiology / Q000473:pathology; D016022:Case-Control Studies; D008078:Cholesterol, LDL / Q000097:blood; D004910:Erythrocyte Membrane / Q000378:metabolism*; D005231:Fatty Acids, Unsaturated / Q000097:blood*; D006801:Humans; D008875:Middle Aged; D019308:Palmitic Acid / Q000097:blood; D012307:Risk Factors; D013229:Stearic Acids / Q000097:blood; D019210:Troponin I / Q000097:blood
chemical_list: C114874:5-octadecenoic acid; D015415:Biomarkers; D008078:Cholesterol, LDL; D005231:Fatty Acids, Unsaturated; D013229:Stearic Acids; D019210:Troponin I; C027369:octadecadienoic acid; D019308:Palmitic Acid