title: Serum paraoxonase 1 activity and oxidative markers of LDL in patients with cardiac syndrome X.
abstract: OBJECTIVE
  Myocardial ischaemia in cardiac syndrome X (CSX) is believed to be due to microvascular dysfunction. Increased oxidative stress is one of the suspected mechanisms of microvascular dysfunction. The aim of this study was to evaluate the oxidative status in patients with CSX, by determining serum paraoxonase-1 (PON 1) activity in addition to LDL-oxidation markers.
  
  
  RESULTS
  This cross-sectional study consisted of patients with CSX (group I, n = 30), patients with coronary artery disease (group II, n = 31), and healthy controls (group III, n = 32). Lipid parameters, PON-1 activity, and LDL oxidation markers (conjugated-diene and thiobarbituric acid-reactive substance-TBARS) were measured. Endothelium-dependent vasodilatation was determined by brachial artery ultrasonography. There were no significant differences in serum LDL, apolipoprotein-B, baseline LDL-diene, and LDL-TBARS levels between groups. There were no differences in both apolipoprotein-A1 and HDL levels between group I and group III. Apolipoprotein-A1 and HDL levels were significantly lower in group II than group I patients (P < 0.001). PON-1 activity was lowest in group II patients. Average PON-1 activity in group I was in between of group II and group Ill. The percent change of LDL-diene levels after stimulation was significantly higher in group II than in groups I and III (P = 0.005 and P = 0.02, respectively). The percent change of LDL-TBARS levels was lowest in group I (P = 0.03). There was a moderate correlation between endothelium-dependent vasodilatation and PON-1 activity in group I (r = 0.43, P = 0.04).
  
  
  CONCLUSIONS
  Enhanced oxidative stress might be one of the causes of impaired endothelial functions resulting in myocardial ischaemia and chest pain in patients with CSX. The relatively preserved HDL and apolipoprotein-A1 levels in patients with CSX might be a protective mechanism against progression of coronary microvascular dysfunction to atherosclerotic coronary artery disease.
authors.affiliation: Ege University School of Medicine, Departments of Cardiology, Izmir, Turkey. meral.kayikcioglu@ege.edu.tr
authors.forename: Meral
authors.initials: M
authors.lastname: Kayikcioglu
authors.forename: Serkan
authors.initials: S
authors.lastname: Saygi
authors.forename: Elif
authors.initials: E
authors.lastname: Azarsiz
authors.forename: Levent H
authors.initials: LH
authors.lastname: Can
authors.forename: Hakan
authors.initials: H
authors.lastname: Kultursay
authors.forename: Eser Yildirim
authors.initials: EY
authors.lastname: Sözmen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001053:Apolipoproteins / Q000097:blood; D043303:Aryldialkylphosphatase / Q000097:blood*; D015415:Biomarkers / Q000097:blood*; D001916:Brachial Artery / Q000000981:diagnostic imaging; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008077:Lipoproteins, LDL / Q000097:blood; D008297:Male; D017566:Microvascular Angina / Q000097:blood* / Q000201:enzymology; D008875:Middle Aged; D018384:Oxidative Stress; D011237:Predictive Value of Tests; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism; D014421:Turkey; D014463:Ultrasonography; D014664:Vasodilation
chemical_list: D001053:Apolipoproteins; D015415:Biomarkers; D008077:Lipoproteins, LDL; D017392:Thiobarbituric Acid Reactive Substances; D043303:Aryldialkylphosphatase