In the present study, we compared the influence of icodextrin (2 g/dL) on uric acid (20 mg/dL) and albumin (1 g/dL) transfer through isolated rabbit parietal peritoneum. In separate series of experiments, we used a mathematical model to calculate the transport rate of solutes from the interstitial to the mesothelial side of peritoneal membrane (I --> M) and in the opposite direction (M --> I) before and after introduction of glucose polymer. In control conditions, the rates of uric acid and albumin passage across the rabbit peritoneum remained constant. Mean values [x +/- standard error of the mean (SEM)] of the diffusive permeability coefficient P were 1.936 +/- 0.324 (I --> M) and 2.078 +/- 0.186 (M --> I) for uric acid and 0.341 +/- 0.066 (I --> M) and 0.389 +/- 0.084 (M --> I) for albumin (all x10(-4) cm/s), respectively. The introduction of glucose polymer into the experimental system did not alter the I --> M transport of either solute; but, in the opposite direction, it caused a 17% decline in the P for uric acid (p < 0.05), and an increase of 77% in the same parameter for albumin (p < 0.03). Hence, I --> M transfer dominated M --> I transfer of uric acid (p < 0.04). In contrast, in albumin transport, M --> I was higher than I --> M (p < 0.02). We conclude that, in vitro, icodextrin modifies the diffusive permeability of the peritoneum and induces transport asymmetry for some small and large solutes.