Association between an Increased Surface Area of Peritoneal Microvessels and a High Peritoneal Solute Transport Rate

Abstract

Objective The peritoneal solute transport rate (PSTR) often increases, especially for small solutes, during long-term peritoneal dialysis (PD) treatment. Although the mechanism by which PSTR increases in PD patients is not known, it is likely that an increased PSTR reflects an increased surface area of the peritoneal capillary and postcapillary venules (microvessels), but this has not previously been investigated. The aim of this study was to clarify the relationship between PSTR and peritoneal microvessel alterations in biopsy specimens of peritoneum obtained from PD patients after various times on PD, and the possible contribution of the duration of PD in relation to these alterations. Design Tissue from the parietal peritoneum was obtained from 22 PD patients (age 48.5± 9.0 years, duration of PD 66.3 ± 46.6 months, incidence of peritonitis 0.3/patient-year). The patients were subdivided into three groups according to duration of PD: zero months (group 0, n = 4), less than 60 months (group I, n = 7), and more than 60 months (group II, n = 11). Methods For each specimen, the relative microvessel area (RVA) calculated as total area of microvessels/total area of peritoneal field, and the relative microvessel number (RVN), calculated as number of microvessels/total area of peritoneal field, were determined. The ratio RVA/RVN was used to assess the average area of microvessels. The PSTR was evaluated for creatinine, glucose, β2-microglobulin, and albumin using the peritoneal equilibration test. Results The dialysate-to-plasma concentration ratio (D/P) for creatinine showed a significant positive correlation with both RVA (rho = 0.77, p < 0.001) and RVA/RVN (rho = 0.51, p = 0.01), but not with RVN. The D/P for β2-microglobulin correlated with RVA (rho = 0.51 p = 0.015) but not with RVN or RVA/RVN. No differences were found between the three groups in the values for RVN, whereas there was an apparent significant increase in RVA with time on PD ( p < 0.001 for group 0 vs both groups I and Furthermore, in high transporters, RVA tended to be higher in group II than in group I. Conclusions The present study demonstrates for the first time that an increased peritoneal solute transport rate (for both creatinine and β2-microglobulin) is associated with an increased surface area of peritoneal microvessels, especially in patients on long-term PD treatment. This indicates that increased vascularization and/or dilatation of peritoneal microvessels may play a key role in the development of a high PSTR.

Relationship Between the −374T/A Receptor of Advanced Glycation End Products Gene Polymorphism and Peritoneal Solute Transport Status at the Initiation of Peritoneal Dialysis

“…Although the mechanism by which PSTR increases in PD patients is not fully understood, angiogenesis might have an important role. Numata et al (7) reported that the peritoneal microvessels area was positively correlated with the D/P Cr obtained by a PET.…”

A Case Study on Peritoneal Dialysis With Biocompatible Peritoneal Dialysis Fluid: Increase in Submesothelial Compact Zone Thickness But Not Vessel Density

“…In the sections stained against CD31, we estimated the twodimensional "microvessel density"; that is, the total number of cross sections of CD31+ microvessels per area of submesothelial compact connective tissue (microvessel profiles/mm 2 ) (21). This parameter is analogous to the "relative microvessel number" used by Numata et al (7) or the "microvessel density" used by Sherif et al (3). It was calculated as the number of microvessel profiles per reference area in five image fields sampled from the submesothelial compact zone in a systematic uniform random manner (using a ¥20 objective).…”

Relationship Between Effluent Levels of β2‐Microglobulin and Peritoneal Injury Markers in 7.5% Icodextrin‐Based Peritoneal Dialysis Solution

“…Hirahara et al (14)(15)(16) focused on the fact that MMP-2 increased in the effluent in the experimental model of sclerosing peritonitis (SP)/ encapsulating peritoneal sclerosis (EPS) in rats and reported that MMP-2 can be a good marker for diagnosing SP/EPS. Numata et al (17) reported that an increased peritoneal solute transport rate (for both creatinine and b2MG) is associated with an increased surface area of peritoneal microvessels. Our results suggest that the increases in multiple peritoneal injury factors owing to ICO dwell, such as proinflammatory cytokines, angiogenic factors, and matrix metalloproteinases, might enlarge the surface area of peritoneal microvessels.…”