Endotoxin effects on transmesothelial transport and intracellular uptake of albumin.

With a 2.9-mM concentration of unlabelled bovine serum albumin (BSA), the FITC-albumin transport (2 mg included) across the omental monolayer (0.48 +/- 0.16 mg/ml/30 min) was found to be significantly reduced as compared with the interstitial BSA concentration (290 microM) as it is the case, e.g., in peritonitis (0.79 +/- 0.09 mg/ml/30 min). Adding 10 micrograms lipopolysaccharide (LPS)/ml from Escherichia coli, serotype 0128:B12, we did not see any differences from the control. Cultured mesothelial cells took up double the amount of FITC-albumin (4.2 +/- 0.13 micrograms/10(5) cells/30 min) and in the presence of LPS the uptake of FITC-albumin was reduced to half the control (2.15 +/- 0.47 micrograms/10(5) cells/30 min). The results reveal the active participation of the mesothelium because high concentrations of BSA reduced exocytosis and stimulated endocytosis. Applying 10 micrograms/ml of LPS turned out to influence endocytosis and to reduce it at a high BSA concentration.