Plasma HDL-cholesterol has an effect on nitric oxide production and arachidonic acid metabolism in the platelet membranes of coronary heart disease patients without LDL-hypercholesterolemia

Aim: to evaluate nitric oxide (NO) production and [³H]arachidonic acid (AA) incorporation into platelet membranes of coronary artery disease (CAD) patients with/without HDL-hypocholesterolemia. Material: 16 healthy controls (C), 14 CAD patients with plasma HDL-hypocholesterolemia (nCAD) and 14 without HDL-hypocholesterolemia (nCAD). All subjects were without peripheral vascular disease and hypertension. The groups were matched for age, sex, BMI. The diagnosis of CAD was substantiated by coronary angiography. Methods: nitric oxide end products xNO (NO₂^- plus NO₃^-) levels in the platelet membranes were measured using anion-exchange chromatography. [³H]AA release from labelled platelets was studied by the method of Neufeld and Majerus; radioactivity was measured by liquid scintillation counting. Levels of plasma HDL-cholesterol (HDL-Ch) and triglycerides were enzymatically determined. Results: significant increase (mean ± SD; Mann-Whitney U test) of [³H]AA incorporation into platelet membrane phospholipids was noted in CAD patients in comparison with healthy subjects (p < 0.001). A correlation (multiple regression analysis) was established between HDL-C level and [³H]AA (r = - 0.58, p < 0.05, n = 28); and between HDL-Ch and NOx levels (r = 0.76, p < 0.05, n = 28) in CAD patients. CAD patients had lower NOx than healthy subjects (p < 0.0001), NOx was lower in the group with decreased HDL-Ch concentration (wCAD 36 ± 5 vs. nCAD 42.3 ± 6 μmol/mg, p < 0.002). Conclusions: CAD patients show decreased ability to produce platelet-derived NO that leads to higher platelet sensitivity to aggregating stimuli. Decreased plasma HDL-Ch may affect AA metabolism and NO production in the platelet membranes of CAD patients without LDL-hypercholesterolemia.