Effects of Peritoneal Rest on Peritoneal Transport and Peritoneal Membrane Thickening in Continuous Ambulatory Peritoneal Dialysis Rats

Abstract

Objective To evaluate the effects of peritoneal rest on peritoneal transport and morphology in a rat model of peritoneal dialysis. Design Twenty-four rats (Sprague-Dawley, male, 250 300 g) were divided into three groups: group 1 (control, n = 6) without dialysis, group 2 (n = 9) sacrificed immediately after 3 weeks of dialysis, and group 3 (n = 9) sacrificed after 4 weeks of peritoneal rest after 3 weeks of dialysis. Both dialysis groups were dialyzed twice daily with an intraperitoneal instillation volume of 25 mL of 3.86% dextrose solution for 3 weeks. Peritonitis was induced by supplementing the dialysis fluid with lipopolysaccharide (5 μg/mL) on days 8, 10, and 12 in both dialysis groups. Peritoneal equilibration tests were performed on each animal at baseline. The equilibration tests were repeated at the 4th and the 8th week of dialysis. Morphometric analyses of the peritoneal membrane were carried out in tissue specimens obtained at the time of sacrifice. Results The DIDo ratio for glucose at two hours in groups 2 and 3 at the beginning of week 4 was significantly lower than at baseline, indicating an increase in peritoneal permeability to glucose after 3 weeks of dialysis. DIDo in group 3 at the beginning of week 8, after 4 weeks of peritoneal rest, was significantly higher than at week 4. The drain volume in groups 2 and 3 at week 4 was significantly lower than at baseline; however, the drain volume in group 3 at week 8 was significantly higher than at week 4. The thickness of the parietal peritoneal membrane in group 3 was significantly greater than in group 1 and less than in group 2 (group 1, 11.4 ± 7.6 μm; group 2, 37.5 ± 18.4 μm; group 3,21.4 ± 12.1 μm). Conclusions Peritoneal rest improves ultrafiltration in rats by decreasing the hyperpermeability of glucose and also reduces the degree of peritoneal thickening. These data suggest that dialysis -induced changes in peritoneal transport and morphology are reversible under the conditions of peritoneal rest in this experimental model.

Pathophysiological Changes to the Peritoneal Membrane during PD-Related Peritonitis: The Role of Mesothelial Cells

“…In a separate study, Rodrigues et al observed a recovery in ultrafiltration following peritoneal rest in 8 of 12 PD patients who had developed hyperpermeability [ 250 ]. In experimental models of PD, a period of 4–12 weeks of peritoneal resting was associated with a marked reduction in peritoneal fibrosis and angiogenesis, and complete remesothelialization of the peritoneal membrane [ 251 , 252 ].…”

Mineralocorticoid receptor blockade ameliorates peritoneal fibrosis in new rat peritonitis model

“…Several animal models of PF or peritoneal sclerosis have been used in intervention studies. These include chlorhexidine gluconate-induced models (19); chronic exposure to 4.25% glucose-based PD solution with or without renal failure (13,60), PD solution with LPS (26,33), or acidic PD solution (38); adenovirus-mediated gene transfer of transforming growth factor-␤ (TGF-␤) models (31,32); and acute bacterial peritonitis models with bacteria originating from skin flora (5) or with Staphylococcus epidermidis (18). However, these bacterial peritonitis models were mainly used to elucidate the mechanisms of inflammation in the membrane and of acute membrane failure.…”

How Can We Standardize Peritoneal Thickness Measurements in Experimental Studies in Rats?

“…Peritoneal biopsy offers useful information about membrane morphology, but no standard method exists to adequately assess peritoneal morphology (5-10). Measurements of peritoneal thickness vary from section to section in the same tissue sample.…”