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Effect of lipopolysaccharide on D-fructose transport across rabbit jejunum
J García-Herrera1, B Abad, M J Rodríguez-Yoldi
1Physiology Unit, Dept. of Pharmacology and Physiology, Veterinary Faculty, University of Zaragoza, Miguel Servet 177, 50013 Zaragoza, Spain.
Objective:
To investigate alterations in the transport of D-fructose across the rabbit jejunum when the gut is exposed in vitro to lipopolysaccharide (LPS), an endotoxin causative agent of sepsis.
Materials And Methods:
D-fructose intestinal transport was assesed employing three techniques: sugar uptake measurements in rings of everted jejunum (micromol/D-fructose/ml cell water), transepithelial flux measurements in Ussing-type chambers (micromol D-fructose/cm2/h) and transport assays in preparation of brush border membrane vesicles (pmoles D-fructose/mg protein). Samples were taken from the bathing solution and from the extracts of the tissue for radioactivity counting.
Results:
Adding LPS (3 microg/ml) to tissue decreased the uptake and mucosal to serosal flux of 5 mM D-fructose across the enterocyte. LPS did not modify sugar uptake across brush border membrane vesicles. The inhibitory effect of LPS was suppressed by W-13 (5 x 10(-6) M), a Ca-calmodulin antagonist, and staurosporine (10(-7) and 10(-6) M) and GF-109203X (10(-6) M) a nonselective and selective protein kinase C (PKC) inhibitor respectively. Tumor Necrosis Factor (TNF-alpha), an immunoregulatory cytokine involved in septic responses occurring during bacterial infection at concentrations 3 x 10(-4) to 3 microg/ml, did not affect the sugar transport.
Conclusions:
LPS can inhibit the intestinal uptake of D-fructose across the rabbit jejunum in vitro by intracellular processes related to PKC and calmodulin protein.