The Suppression of Peritoneal Advanced Glycosylation End Product Formation by Intraperitoneal Aminoguanidine / 대한신장학회잡지

BACKGOUND: The purpose of the study was to evaluate the effect of aminonguanidine on the inhibition of advanced glycosylation end product (AGE) formation and the expression of peritoneal vascular endothelial growth factor (VEGF). Then we analyzed the functional and morphological alterations of peritoneal membrane during long-term PD in rats. METHODS: Male Sprague-Dawley rats were randomly divided into 3 groups:group I (n=6), control rats with PD catheter but not dialyzed; group II (n=9), rats dialyzed with 4.25% glucose solution for all exchanges; group III (n=9), rats dialyzed with 4.25% glucose solution containing aminoguanidine (25 mg/kg) for all changes. Dialysis changes were performed 3 times a day with 25 mL/each exchange for 12 weeks. Immunostaining was performed using a monoclonal anti-AGE antibody and a polyclonal anti-VEGF antibody. One-hour peritoneal equilibration test were performed at every 4-week for the comparison of peritoneal transport characteristics. RESULTS: Expressions of peritoneal AGE and VEGF in dialyzed groups (group IIand III) were higher compared to control group. The level of AGE immunostaining in group III was significantly lower than in the group II. But peritoneal VEGF expression did not differ between the dialyzed groups. In dialyzed groups, D/DO glucose was significantly lower whereas D/P urea was significantly higher than in the control group. On linear regression analysis, peritoneal AGE and VEGF accumulation were directly correlated with D/DO glucose and D/P urea nitrogen. But there was no statistical significance in D/DO glucose and D/P urea nitrogen between the dialyzed groups. CONCLUSION: Peritoneal accumulation of AGE and VEGF increased with time on CAPD in dialyzed groups. Intraperitoneal aminoguanidine was greatly suppressed peritoneal AGE accumulation but no attenuated long-term dialysis related peritoneal hyperpermeability. The VEGF formation may be one of the several mediators resulting the functional deterioration of the peritoneal membrane in long-term peritoneal dialysis.

Altered Expression of Peritoneal Aquaporin-1 and Water Transport during Long-term Peritoneal Dialysis in Rats / 대한신장학회잡지

BACKGROUND: The present work was designed to examine the altered expression of peritoneal AQP-1 and water transport of peritoneal membrane during the long-term peritoneal dialysis with hypertonic glucose solution in rats. METHODS: Eighteen Sprague-Dawley male rats were randomly divided into 2 groups: control rats (n=6) with peritoneal catheter but not dialyzed; rats with peritoneal dialysis (PD) (n=12) were dialyzed with 4.25% glucose dialysate for all exchanges. Before completion of the study, 4 animals in PD group were euthanized owing to nonfunctional catheters or peritonitis, leaving 14 animals for the analysis. Dialysis exchanges were performed 3 times a day with 25 mL/each exchange for 12 weeks. Immunoperoxidase staining was performed using monoclonal anti-AGE antibody and polyclonal anti-AQP-1 antibody. The slides were read by 5 different examiners in a blind fashion. The staining intensity was graded semiquantitively from 0 to 3. The peritoneal membrane function was assessed by performing one-hour peritoneal equilibration tests every 6 week for comparing transport characteristics. Peritoneal membrane transport rate was assessed by D/P of urea nitrogen and D/Do of glucose. Water transport of peritoneal membrane was assessed by D/P of sodium at 12 week. RESULTS: The expression of peritoneal AQP-1 was increased in rats with PD, compared to control rats. Consistent with this, D/P of sodium in rats with PD was significantly decreased compared to control rats (0.58+/-0.04 vs 0.86+/-0.07, p<0.05), indicating high peritoneal water permeability in response to long-term peritoneal dialysis. Moreover, rats with PD were associated with significantly lower D/Do of glucose and higher D/P of urea nitrogen, suggesting high peritoneal membrane transport. CONCLUSION: High expression of peritoneal AQP-1 was associated with an increased peritoneal water permeability in response to long-term peritoneal dialysis with 4.25% glucose for 12 weeks. The underlying mechanisms for the increased AQP-1 expression need to be examined whether it is due to the continuous exposure to the dialysis solution containing high glucose concentration itself or compensatory effects of slowly developed concomitant ultrafiltration failure in chronic peritoneal dialysis.

Pirfenidone Treatment During Peritoneal Dialysis Reduces Peritoneal Fibrosis in Rats / 대한신장학회잡지

BACKGROUND: Peritoneal fibrosis is one of the most serious complications in patients undergoing continuous ambulatory peritoneal dialysis (CAPD). In order to determine the effects of pirfenidone treatment for reducing peritoneal fibrosis, we examined the changes of peritoneal permeability (for glucose and urea nitrogen) and peritoneal thickness in a rat model of chronic peritoneal dialysis. METHODS: Thirty male Sprague-Dawley rats were divided into the following three groups: group I (n= 6), control rats with normal chow; group II (n=10), rats dialyzed with standard 4.25% glucose solution maintained on normal chow; group III (n=8), rats dialyzed with standard 4.25% glucose solution and maintained on pirfenidone-mixed chow (pirfenidone 350 mg/kg/day). Dialysis exchanges were performed three times a day with an instillation volume of 25 mL for a period of 12 weeks. Morphometric analysis of the peritoneal membrane were carried out in tissue specimens obtained at the time of sacrifice. One- hour peritoneal equilibration test was done at the beginning and the end of the study to compare the transport characteristics in these groups. RESULTS: The peritoneal permeability of glucose and urea nitrogen was much higher in rats subjected to peritoneal dialysis (both in group II and group III), as compared with control rats (group I). In group II where rats received peritoneal dialysis without pirfenidone treatment, rats had the highest level of peritoneal permeability for glucose and urea nitrogen, suggesting the peritoneal hyperpermeability. In contrast, rats in group III dialyzed with pirfenidone treatment had an improved peritoneal hyperpermeability indicating that pirfenidone treatment may have a protective effect against peritoneal hyperpermeability. Consistent with this, rats subjected to peritoneal dialysis were associated with a marked thickening of peritoneal membrane in both parietal (group I: 13.7+/-3.3 micrometer, group II: 59.5+/-26.2 micrometer, group III: 36.5+/-11.2 micrometer) and visceral (group I: 3.1+/-0.9 micrometer, group II: 10.9+/-5.2 micrometer, group III: 6.1+/-1.7 micrometer) peritoneum. In particular, submesothelial region in peritoneum was significantly thickened by accumulation of collagen, demonstrated by Masson's trichrome staining. Pirfenidone treatment during peritoneal dialysis, however, significantly reduced the accumulation of collagen in mesothelial region of the parietal peritoneum. CONCLUSION: Peritoneal dialysis with high glucose containing dialysate is associated with significant peritoneal collagen accumulation in mesothelial region and an increased peritoneal permeability for glucose and urea nitrogen. In contrast, pirfenidone treatment during peritoneal dialysis significantly reduces peritoneal thickness as well as peritoneal hyperpermeability, suggesting a protective effect against peritoneal fibrosis induced by chronic peritoneal dialysis.