| BackgroundCadiovascular disease remains the major cause of mortality and morbidity in maintenance hemodialysis patients(MHD). Recent evdience suggests that endothelial dysfunction proceeds to and exacerbates atherosclerosis. It remains unknown whether hemodialysis(HD) or hemodiafiltration(HDF) per se causes endothelial dysfunction. We aimed to investigate the effect of hemodialysis or hemodiafiltration 6 times continously as well as after a single treatment on endothelial function.MethodsWe evaluated endothelial function estimated by flow-mediated vasodialation(FMD) during hyperemia using high-resolution ultrasound combined with endothelial injury markers—soluble endoehelial protein C receptor(sEPCR),soluble thrombomodulin(sTM) as well as inflammatory markers—interleukin-6(IL-6), high sensitive C-reactive protein(hs-CRP) and other blood chemistry indicators..For the first experiment,20 MHD patients underwent HD or HDF for 6 times in two weeks in a random selection. FMD and blood chemistry measurements were done immediately before and after HD/HDF. Then they underwent hemodialysis for 6 times as a elution process. For the second experiment, the protocol of the first experiment was repeated in them by a crossover design.20 chronic kidney disease patients of stage 5(CKD stage 5)and healthy controls were evaluated the FMD and blood chemistry in the same way as the comparison of MHD patients.Results1. FMD were not different with healthy controls except the pre-and post value of the 6th treatment of HD(P＜0.05). FMD were significantly impaired in CKD stage 5 patients compared with healthy controls and the post value of MHD patients in 1 st and 6th HDF sessions(P＜0.01). There were no differences between pre-and post FMD levels of two HD sessions. FMD were significantly elevated after a single session at the 1st(P＜0.05) and 6th(P＜0.01) treatment of HDF.2. Plasma level of sEPCR in HD period and pre-levels in HDF period of MHD patients were significantly higher than healthy controls(P＜0.01). There were no differences between post levels of HDF with healthy controls, however. Levels of sEPCR in CKD stage 5 patients were also significantly higher than healthy controls(P＜0.01). Except for the pre-levels of 1st HD session, levels of sEPCR were all higher than CKD stage 5 patients(P＜0.01). While there were no obvious differences between post levels of 1 st HDF and pre-levels of the 6th HDF with CKD stage 5 patients. Furthermore, the post level of last HDF had become significantly lower than CKD stage 5 patients(P＜0.01). There were no differences between pre-and post sEPCR levels of two HD sessions. While it decreased significantly after a single session in both HDF sessions(P＜0.01). Furthermore, the post level of 1st and the 6th HDF as well as the pre-level of the 6th HDF session were all significantly lower compared with those in HD sessions(P＜0.01).3. sTM levels in MHD and CKD stage 5 patients were both significantly higher than that in healthy controls (P＜0.01), and the levels of MHD patients were also significantly higher than that of CKD stage 5 patients (P＜0.01). The post levels of sTM increased significantly compared to its pre-levels in the 6th HD session in MHD patients (P＜0.01),and there were no differences between pre-and post sTM levels of two HDF sessions. However, the post level of 1st and 6th HDF (P＜0.01) as well as the pre-levels of 6th HDF (P＜0.05) were lower than those in the same phases of HD.4. Plasma level ofβ2-MG decreased in MHD patients after a single HD or HDF session(P＜0.01). Futhermore, the post level of 1st HDF along with the pre-and post levels of 6th HDF were significantly lower compared with the same session of HD treatments (P70.01).5. IL-6 levels in MHD and CKD stage 5 patients were boht higher than healthy controls(P＜0.01). IL-6 levels in MHD patients had no significantly difference in pre-and post value of a single HD or HDF session. While the post level of the 6th HDF session were significantly lower than that of HD session(P＜0.01).6. The pre-and post hs-CRP levels of 1st HD and pre-value of the 6th HDF session in MHD patients were higher than that of healthy controls(P＜0.05). The pre-and post value of the 6th HD and 1 st HDF session as well as the post value of 6th HDF and CKD stage 5 patients were significantly higher than that of healthy controls (P＜0.01). No difference was found between the CKD stage 5 patients and MHD patients in plasma hs-CRP levels. Hs-CRP levels were all elevated after a single session of HD of HDF(P＜0.01).7. Correlation analysis showed that age (r=-0.318), BMI (r=-0.324), hs-CRP (r=-0.364) was negatively correlated with FMD (P＜0.05); Alb levels was significantly positively correlated(r=0.430, P＜0.01) with FMD. However, multiple linear regression showed that only Alb had a linear dependence with FMD (standardized regression coefficientβ=0.430, P＜0.01). 8. The degree of FMD improved (ΔFMD) in MHD patients during HDF session were negatively correlated with the degree of elevated sTM levels(ΔsTM)(standardized regression coefficientβ=-0.477, P=0.034).Conclusions1. MHD patients have impaired endothelial function. Compared with HD, HDF could improve the impaired endothelial function via a better elimination of inflammatory molecules and middle molecular uremic toxins, which attenuate the inflammation and oxidative stress in vivo thus provide an improved internal environment for MHD patients.2. FMD levels of CKD stage 5 patients were significantly lower than that of healthy controls, as well as that compared with MHD patients, which may be related to malnutrition, anemia and poor control of inflammation states.3. FMD levels of ESRD patients is correlated with nutrition (Alb), anemia (Hb) and inflammatory status (IL-6, hs-CRP). Actively correct malnutrition and anemia, reduce microinflammatory state may have positive implication for the improvement of FMD.
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