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Renalase, secreted by the kidney, degrades catecholamines and may play a role in the regulation of sympathetic tone and blood pressure. The aim of this study was to assess serum renalase levels in hemodialysis patients and their relationship to blood pressure control, type of antihypertensive therapy and the presence of residual renal function. Results: The mean serum renalase in the study cohort was significantly higher than in the control group (27.53 ± 7.18 vs. 3.86 ± 0.73 µg/ml, p < 0.001). The serum renalase concentration was significantly lower in patients with residual renal function when compared to the anuric patients. The type of hypotensive treatment (β-blockers, ACE inhibitors or AT1 receptor blockers) did not affect renalase levels. There was a significant inverse correlation between the serum renalase and age (r = –0.28, p = 0.023) and residual renal function (r = –0.327, p = 0.001). Renalase was not related to blood pressure, heart rate or hemodialysis vintage. Conclusion: Elevated renalase levels in HD patients may be due toimpaired kidney function. Further studies are needed to prove or disprove the possible role of renalase in the pathogenesis of hypertension in patients with kidney diseases.

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Background: hRenalase may degrade catecholamines and regulate sympathetic tone and blood pressure (BP). The aim of the study was to assess dopamine (DA), norepinephrine (NE), and renalase in 75 hemodialysis (HD) and 26 peritoneal dialysis (PD) patients and their correlations with heart rate (HR), BP, a type of hypotensive therapy, and residual renal function. Methods: Renalase, DA, NE were studied using commercially available assays. Results: Renalase and NE were higher and DA was lower in dialyzed groups comparing to healthy volunteers. Hemodialysis patients had lower NE and higher renalase level. Norepinephrine was higher in anuric patients in HD group. Renalase correlated with dialysis vintage and inversely with residual diuresis. Dopamine correlated with residual diuresis in the whole study cohort, with HR in PD patients, with renalase in HD patients. Norepinephrine correlated with aortic diameter in PD patients. Norepinephrine was significantly higher in patients with coronary artery disease (CAD) in HD group. Hemodialysis population with CAD had lower NE and higher DA and renalase level than their PD counterparts. In the follow up, 27% of HD group died. Cardiac death was diagnosed in 17% and there was higher renalase level than in noncardiac death. Conclusions: Elevated level of circulating renalase in dialysis patients is rather related to kidney function and the sympathetic nervous system hyperactivity found in this population. The real excess of renalase in the pathogenesis of cardiovascular disorders in patients with chronic kidney disease still remains to be proven. If confirmed, it may give a new way for pathophysiological therapy.

IntroductIon The endothelial cell layer is the "guardian" of molecular traffic between the blood and surrounding tissue, and endothelial integrity plays a pivotal role in many aspects of vascular function, e.g., control of vasomotor tone and permeability. Cardiovascular risk factors such as hypertension may cause endothelial dysfunction and even disintegration, finally resulting in small vessel disappearance (vascular rarefaction) and tissue hypoxia. In patients with chronic kidney diseases (CKD), ongoing endothelial damage in the capillary system of the renal medulla and accompanying vascular rarefaction are thought to be central processes toward progressive kidney damage. 1,2 Endothelial dysfunction is highly prevalent in both cardiovascular disease and CKD. 3-5 Among various functions of the kidney, it is also an endocrine organ. In 2005, Xu et al. 6 presented in their landmark study the history of