Biochemical parameters of endothelial dysfunction in cardiological syndrome X

The endothelial dysfunction in cardiological syndrome X has been studied mainly by invasive methods and by measuring vasoactive mediator (nitric oxide (NO), endothelin-1) levels. Other parameters evaluating this dysfunction (defined as an imbalance between vascular relaxing and contracting factors, between procoagulant and anticoagulant or growth-inhibiting and growth-promoting substances) have not been used.

Twenty-five non-diabetic patients (16 men, 9 women) with cardiological syndrome X and 10 healthy volunteers (5 men, 5 women) were examined. Biochemical parameters: ET-1, the end products of nitric oxide metabolism (NOx), VEGF, vWF, betaTG, tPA, PAI-1 were measured before and during an ECG exercise tolerance test. The blood concentrations of testosterone and estradiol in men and LH, FSH and estradiol in women were tested.

A significantly lower basal concentration of NOx (p=0.01), lower basal NOx/ET-1 ratio (p<0.05) and higher levels of VEGF (p<0.05) were observed in patients with cardiological syndrome X. The male patients also had higher concentrations of estradiol (p<0.05). A significant decrease in tPA concentration and increase in betaTG was noticed during exercise, but with no differences between the study groups.

Endothelial dysfunction in cardiological syndrome X manifests mainly in the regulation of vessel wall tonus. which was revealed by the decrease of NOx level and NOx/ET-1 ratio. VEGF elevation in syndrome X may result from chronic tissue ischaemia due to endothelial dysfunction. Exercise augments the prothrombotic activity of the blood, since a significant elevation in betaTG and decrease in tPA were observed after exercise.