In Vivo Peritoneal Chamber: Linking Structure and Transport Function

Abstract

Objective

The present study aimed to develop an animal model of chronic peritoneal exposure that directly links transport with the tissue involved.

Methods

Daily, rats were intraperitoneally infused through subcutaneous ports with 20 mL of these solutions: isotonic Krebs (K), K + 2.5% mannitol (M), K + 2.5% N-acetylglucosamine (NAG). Controls included catheter-only (CC) and age-control rats (AC). After 2 months, each rat was anesthetized and a plastic chamber was affixed to the abdominal wall serosa to isolate a portion of the peritoneum for transport studies. In the first 90 minutes, a hypertonic solution (approximately 500 mosm/kg) containing ¹⁴C-mannitol was placed in chamber. The volume and ¹⁴C concentration were measured to determine the rate of osmotic flux (flow/Area_chamber) into the chamber and the flux of mannitol from the chamber to the tissue. At 90 minutes, fluorescein isothiocyanate conjugate (FITC)–albumin was given intravenously. The rate of appearance of that substance in the chamber was measured over a period of 180 minutes and divided by Area_chamber to determine the average flux. After the rat was humanely killed, the tissue under the chamber was collected for analysis of its hyaluronan concentration ([HA]).

Results

All data are given as mean ± standard error:

Group Osmotic (μL/cm²) Flux per hour

Mannitol (/cm²) Albumin (/cm²) [HA] (μg/g dry)

AC 69.9±14.0 0.043±0.004 0.0114±0.0012 1247±136

CC 65.5±8.0 0.040±0.013 0.0105±0.0027 1360±157

K 47.0±11.5 0.067±0.015 0.0116±0.0027 1134±160

M 101±20 0.044±0.017 0.0300±0.0120 1146±157

NAG 72.6±11.4 0.052±0.006 0.0188±0.0144 1240±157

Conclusions

In the present pilot study, no significant correlations were observed, but the number of animals in each group was small (n = 3 – 4). Nevertheless, the results demonstrate the ability of the chamber technique to determine transperitoneal transport of water, small solutes, and protein, and to link those values directly to the structure of the tissue lying below the chamber. Thus, chronic treatment can be directly correlated with peritoneal structure and transport function.