G. Hecht et A. Koutsouris, Enteropathogenic E-coli attenuates secretagogue-induced net intestinal iontransport but not Cl- secretion, AM J P-GAST, 39(3), 1999, pp. G781-G788
Citations number
27
Categorie Soggetti
da verificare
Journal title
AMERICAN JOURNAL OF PHYSIOLOGY-GASTROINTESTINAL AND LIVER PHYSIOLOGY
Enteric bacterial pathogens often increase intestinal Cl- secretion. Entero
pathogenic Escherichia coli (EPEC) does not stimulate active ion secretion.
In fact, EPEC infection decreases net ion transport in response to classic
secretagogues. This has been presumed to reflect diminished Cl- secretion.
The aim of this study was to investigate the influence of EPEC infection o
n specific intestinal epithelial ion transport processes. T84 cell monolaye
rs infected with EPEC were used for these studies. EPEC infection significa
ntly decreased short-circuit current (I-sc) in response to carbachol and fo
rskolin, yet I-125 efflux studies revealed no difference in Cl- channel act
ivity. There was also no alteration in basolateral K+ channel or Na+-K+-2Cl
(-) cotransport activity. Furthermore, net Cl-36(-) flux was not decreased
by EPEC. No alterations in either K+ or Na+ transport could be demonstrated
. Instead, removal of basolateral bicarbonate from uninfected monolayers yi
elded an I-sc response approximating that observed with EPEC infection, whe
reas bicarbonate removal from EPEC-infected monolayers further diminished I
-sc. These studies suggest that the reduction in stimulated I-sc is not sec
ondary to diminished Cl- secretion. Alternatively, bicarbonate-dependent tr
ansport processes appear to be perturbed.