Hyaluronan preserves peritoneal membrane transport properties

Background: We have shown that intraperitoneal (IP) addition of hyaluronan (HA) in a single dwell study in rat could increase peritoneal fluid removal by decreasing the peritoneal fluid absorption rate. In this study, we inve stigated the impact of repeated use of HA on peritoneal membrane transport characteristics. Methods:Twelve male Sprague-Dawley rats received a once-daily IP injection of 25 mt 4.25% glucose dialysis solution without (HP group, n = 6) or with 0.025% HA (HA group, n = 6) for 1 week. Forty-eight hours after the last in jection, a 4-hour dwell using 25 mt 4.25% glucose dialysis solution with IP volume marker and frequent dialysate and blood samplings was performed in each rat as well as in rats that did not receive any injection (control gro up, n = 8). Results: Although the IP volumes were significantly lower in the HP and HA groups compared to the control group, IP volume in the HA group was signifi cantly higher than in the HP group. Net ultrafiltration at 4 hours was 5.6 +/- 1.3 mt, 10.2 +/- 1.8 mt, and 13.2 +/- 0.6 mt for the HP, HA, and contro l group, respectively. The peritoneal fluid absorption rate decreased by 45 % in the HA group compared to the HP group. There was no significant differ ence in peritoneal fluid absorption rate between the HA and the control gro up. No difference was found in the direct lymphatic absorption rate between the HP and HA groups [0.010 +/- 0.003 mL/minute in the HP group and 0.011 +/- 0.004 mL/min in the HA group] although they were both higher than that of the control group (0.004 +/- 0.001 mL/min). The solute transport rates w ere in general significantly higher in the HP group compared to the HA end control groups, and there was no significant difference between the latter two groups, except that protein transport rate was significantly lower in t he HA group compared to the control group. Conclusions: The present study suggests that (1) repeated exposure to hyper tonic glucose-based dialysis solution results in increased peritoneal solut e transport rates, as well as increased peritoneal fluid absorption rates; and (2) these changes, reflecting a highly permeable peritoneal membrane, w ere ameliorated by repeated IP addition of hyaluronan. The similar changes in the direct lymphatic absorption rate in rats that received daily IP inje ction of dialysis solution suggest that direct peritoneal lymphatic absorpt ion was not influenced by hyaluronan.