Asymmetric Dimethylarginine (ADMA) and Soluble Vascular Cell Adhesion Molecule 1(sVCAM-1) as Circulating Markers for Endothelial Dysfunction in Patients with Pheochromocytoma

Background: Endothelial dysfunction is a common feature of hypertension and is associated with reduced nitric oxide bioavailability. The endogenous inhibitor of nitric oxide syntase, asymmetric dimethylarginine (ADMA), and soluble adhesion molecules such as vascular cell adhesion molecule 1 (sVCAM-1) have been established as markers of endothelial dysfunction in a number of pathologic conditions including essential hypertension. There is little information, however, about these markers in endocrine hypertension. Objective: To investigate the levels of circulating ADMA and sVCAM-1 in patients with pheochromocytoma. Patients and methods: Serum ADMA and sVCAM-1 concentrations were assayed by ELISA technique in 18 patients with pheochromocytoma, 18 patients with essential hypertension (EH) and 18 healthy subjects serving as a control group. Results: ADMA and sVCAM-1 levels were significantly elevated in pheochromocytoma patients compared to normotensive healthy controls (0.479 +/- 0.072 vs. 0.433 +/- 0.054 mu mol/l, p = 0.037 and 690 +/- 181 vs. 577 +/- 108 ng/ml, p = 0.03, respectively). Patients with EH also had higher ADMA concentrations than the control group, but the difference was not significant (0.476 +/- 0.075 vs. 0.433 +/- 0.054 mu mol/l, p = 0.06). No associations were found between the levels of ADMA, sVCAM-1 and some potential risk factors for endothelial dysfunction. Conclusion: Endothelial function is impaired in patients with pheochromocytoma as indicated by the elevated circulating levels of ADMA and sVCAM-1. The lack of association of these markers with cateholamines, glucose and lipid abnormalities together with their comparable levels in EH patients suggests that endothelial dysfunction is most likely related to hypertension itself.