Increased reduction of dimethylarginines and lowered interdialytic blood pressure by the use of biocompatible membranes

Hypertension contributes to cardiac and cerebrovascular complications in ND patients. Endogenous inhibitors of nitric oxide synthase accumulate in ren al failure and may interfere with the regulation of vascular tone. We inves tigated the elimination of asymmetric dimethylarginine (ADMA) by using bioc ompatible Polyamide S(TM) membranes in low-flux (Polyflux 6L) or high-flux (Polyflux 14S) hemodialysis or hemodiafiltration (HDF) compared with hemodi alysis with cellulosic membranes. Removal rates for ADMA, symmetric dimethy larginine (SDMA), and beta2-microglobulin significantly increased in HDF. T he plasma total amino acid concentration and the arginine/ADMA ratio increa sed, and the mean 24-hour blood pressure decreased during the study. In a s econd study, we investigated whether plasma amino acids and interdialytic b lood pressure are influenced by the use of a biocompatible membrane and HDF . Seventeen end-stage renal disease patients were treated for six weeks wit h hemodialysis using cellulosic membranes, six weeks with low-flux hemodial ysis using Polyflux 6L, and six weeks with HDF using Polyflux 14S. Only in the diabetic patients were the hemoglobin concentration (from 10.6 +/- 1.5 to 11.9 +/- 0.6 mg/dL) and hematocrit (from 33.6 +/- 1.9 to 36.2 +/- 1.5%) increased significantly, whereas the mean 24-hour systolic blood pressure d ecreased (from 154 +/- 22 to 129 +/- 18 mm Hg). No significant changes were observed in nondiabetic patients. We conclude that primarily diabetic pati ents seem to benefit from the use of biocompatible membranes-most in HDF-af ter a period of six weeks. The regulation of nitric oxide pathways by ADMA removal and changed ADMA/arginine ratio might be contributing factors. Furt her prospective studies are required to show whether the long-term applicat ion of HDF or other changes of dialysis treatment modalities may help to im prove well-being, morbidity, and mortality in hemodialysis patients.