Relationship of ENOS and RAS Gene Polymorphisms to Initial Peritoneal Transport Status in Peritoneal Dialysis Patients

Background: Peritoneal membrane permeability is of major importance for adequate dialysis and fluid balance in peritoneal dialysis (PD) therapy. The peritoneal capillary endothelium plays a key role in peritoneal transport. Nitric oxide derived from endothelial cells is related to the maintenance of vascular permeability. We investigated the relationship between the endothelial nitric oxide synthase (ENOS) gene polymorphism, the renin-angiotensin system (RAS) gene polymorphisms, and initial peritoneal transport type in PD patients. Methods: This study included 74 incident continuous ambulatory PD patients. The ENOS gene polymorphism was identified at the 4a/b variable number of tandem repeats in intron 4. Genetic polymorphisms of the renin-angiotensin system were performed for the angiotensin-converting enzyme I/D, angiotensinogen M235T, and angiotensin II type 1 receptor A1166C and type 2 receptor C3123A by polymerase chain reaction. Patients were divided into two groups according to the initial peritoneal equilibration test results performed within 3 months of PD therapy: group 1 consisted of high/high average transporters (n = 41), and group 2 consisted of low/low average transporters (n = 33). Results: Demographic, clinical, and laboratory data were similar between the two groups (p > 0.05). Group 1 had a significantly higher prevalence of the ENOS b/b genotype than group 2 (78% vs. 48.5%, p < 0.008). In contrast, group 2 had a significantly greater prevalence of the ENOS a/a+a/b genotype than group 1 (51.5% vs. 22%, p < 0.008). Genetic polymorphisms of the renin-angiotensin system were not associated with initial peritoneal transport type (p > 0.05). Conclusions: Modulation of the nitric oxide activity via the ENOS a/b polymorphism may have a considerable effect on the basal peritoneal permeability.