Ultrafiltration Failure and Impaired Sodium Sieving during Long-Term Peritoneal Dialysis: More than Aquaporin Dysfunction?

Abstract

Fifteen years ago, our group reported the case of a 67-year-old man on peritoneal dialysis for 11 years, in whom ultrafiltration failure and impaired sodium sieving were associated with an apparently normal expression of aquaporin-1 (AQP1) water channels in peritoneal capillaries. At that time, AQP1 dysfunction This single copy is for your personal, non-commercial use only. For permission to reprint multiple copies or to order presentation-ready copies for distribution, contact Multimed Inc. at marketing@multi-med.com 228 SHORT REPORTS MARCH 2016 -VOL. 36, NO.

A Large Intraperitoneal Residual Volume Hampers Adequate Volumetric Assessment of Osmotic Conductance to Glucose

“…Osmotic conductance to glucose characterizes every individual membrane and reflects its intrinsic ability to transport water in response to the crystalloid osmotic gradient induced by glucose. Recent data from mathematical modeling and structure-function correlations in patients on long-term PD have highlighted the importance of monitoring water transport to detect progressive fibrosis in the peritoneal interstitium and identify those at risk of encapsulating peritoneal sclerosis (EPS) (10 11 12 13 14-15). Here, we found that a large RV leads to significant overestimation of OCG using the double mini-PET, potentially reducing the ability of OCG to identify patients at risk for EPS.…”

“…Mathematical modeling combined with data from experimental models of PD have established that water transport across the peritoneal microvascular endothelium induced by glucose-based solutions occurs both at the level of interendothelial junctions ( para -cellular pathway, or ‘small-pore'–mediated, solute-coupled, water transport [SPWT]) and across endothelial aquaporin water channels ( trans -cellular pathway, or ‘ultrasmall pore'–mediated, free-water transport [FWT]) (6–9). In baseline conditions, it is assumed that the peritoneal interstitium does not influence peritoneal transport (6); on the other hand, the development of a fibrotic interstitium in long-term PD patients restricts osmotic water flow across the membrane, thereby altering sieving of the sodium dialysate and OCG (10 11 12 13 14-15).…”

Alteration of membrane complement regulators is associated with transporter status in patients on peritoneal dialysis

“…Fast transporters achieve rapid and complete equilibration of small solutes due to a larger functional membrane surface area and higher membrane permeability [ 26 , 53 ]. However, fast transporters quickly lose their osmotic gradient and achieve poor UF because dialysate glucose is rapidly absorbed from the peritoneal cavity [ 54 , 55 ]. The expression of CD55 on vessels in this study indicates a vasculature disturbance in patients in the HA/H group.…”

Length of Time on Peritoneal Dialysis and Encapsulating Peritoneal Sclerosis — Position Paper for ISPD: 2017 Update

“…The combination of functional and structural analysis of the membrane of patients with EPS demonstrated that reduced osmotic water transport is directly related to the degree of fibrosis and to changes in collagen density and structure in the peritoneal interstitium (88), in line with predictions based on the serial pore-membrane/fiber matrix and distributed models (94 95-96). Of note, the low osmotic conductance and abolition of sodium sieving are not associated with any change in the expression of aquaporin-1 (AQP1) water channels in the peritoneal capillaries of patients with EPS (97,98).…”

“…As is clearly shown in the studies of the epidemiology of EPS, duration of PD is strongly associated with EPS risk. In competing risks prediction models for patients in ANZDATA 3 and 5 years after the start of PD using age and primary renal disease as predictors of mortality and duration of PD as a predictor of EPS, most of the variability in EPS incidence was explained (unpublished conductance and abolition of sodium sieving are not associated with any change in the expression of aquaporin-1 (AQP1) water channels in the peritoneal capillaries of patients with EPS (97,98).…”