To evaluate the rate of glucose diffusion through separate transport barriers against the net solute transport during peritoneal dialysis, a layer of mesothelium with adjacent connective tissue from rabbits was investigated in a modified Ussing chamber. The transport of glucose of initial feed concentrations 1.2, 2.0 and 3.6 g% (in Hanks' fluid) from the mesothelial to the interstitial side of the membrane was studied with the mesothelium intact or denuded (2.5 mmol/l sodium deoxycholate) peritoneum for 120 min or 150min, respectively. A mathematical model was used to calculate the diffusive permeability (P) for the investigated specimens. The model assumed diffusion transport between two well mixed compartments, and took into account the change of the concentration in the feed solution and the correction for sampling. The transport rates were stable across all studies with the intact peritoneum, and P was 2.62±1.18x10-4 cm/s (mean±SD). This P value used for a membrane area 1.75 m2, as assumed usually for CAPD patients, yields glucose clearance through the investigated barrier of 4.58 ml/s, which is higher than value reported from clinical transport studies. Removal of the mesothelium increased the transport coefficient (P) by about 11, 40% and 90% for the 1.2, 2.0 and 3.6 g% glucose concentration, respectively. We conclude that the mesothelium and adjacent connective tissue layer may be an important transport barrier.

Keywords: peritoneal transport, mesothelium, interstitium, Diffusion, Glucose