INVITRO STUDIES OF INTESTINAL ENDOTOXIN ABSORPTION .1. KINETICS OF ABSORPTION IN ISOLATED EVERTED GUT SAC

  • 1 January 1977
    • journal article
    • research article
    • Vol. 72  (3) , 434-439
Abstract
Endotoxin can apparently cross gut epithelium, but precise quantitation has not been possible. These studies measured quantitatively the mucosal to serosal unidirectional flux of [Escherichia coli] endotoxin with the use of an in vitro rat gut sac preparation. 51Cr-labeled endotoxin was placed in the mucosal bath in concentrations from 0.05-2.0 mg/ml. Over a 2 h period a small amount of endotoxin was transported transmurally which was shown chromatographically to be similar to the starting material and which retained its toxic and immunogenic properties. At first the presence of 2.0 mg/ml endotoxin in the mucosal bath did not significantly alter the tissue''s histology or permeability to 3-O-methyl-D-glucose. When unidirectional fluxes were measured, however, the flux was not proportional to the endotoxin concentration as would be expected with a passively permeable solute, but rather its transport system became saturated, displaying a maximum transport rate of 4.72 (.mu.g/cm) per 2 h and a Km of 0.425 mg/ml. The isolated gut sac provides an excellent model for the precise study of factors involved in endotoxin absorption.

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