Correlating structure with solute and water transport in a chronic model of peritoneal inflammation

Abstract

To study the process of chronic peritoneal inflammation from sterile solutions, we established an animal model to link structural changes with solute and water transport. Filtered solutions containing 4% N-acetylglucosamine (NAG) or 4% glucose (G) were injected intraperitoneally daily in 200- to 300-g rats and compared with controls (C). After 2 mo, each animal underwent transport studies using a chamber affixed to the parietal peritoneum to determine small-solute and protein mass transfer, osmotic filtration, and hydraulic flow. After euthanasia, parietal tissues were sampled for histological analysis, which demonstrated significant differences in peritoneal thickness (μm; C, 42.6 ± 7.5; G, 80.4 ± 22.3; NAG, 450 ± 104; P < 0.05). Staining for VEGF correlated with CD-31 vessel counts (no./mm2: C, 53.1 ± 16.1; G, 166 ± 32; NAG, 183 ± 32; P < 0.05 ). Tissue analysis showed treatment effects on tissue hyaluronan (μg/g: C, 962 ± 73; G, 1,169 ± 69; NAG, 1,428 ± 69; P < 0.05) and collagen (μg/g: C, 56.9 ± 12.0; G, 107 ± 12; NAG, 97.6 ± 11.4; P < 0.05) but not sulfated glycosaminoglycan. Transport experiments revealed no significant differences in mannitol transfer or osmotic flow. Changes were seen in hydrostatic pressure-driven flux (μl·min−1·cm−2: C, 0.676 ± 0.133; G, 0.317 ± 0.124; NAG, 0.284 ± 0.117; P < 0.05) and albumin transfer (μl·min−1·cm−2: C, 0.331 ± 0.028; G, 0.286 ± 0.026; NAG, 0.229 ± 0.025; P < 0.04). We conclude that alteration of the interstitial matrix correlates with diminished hydraulic conductivity and macromolecular transport.