Effects of a tyrosine phosphatase inhibitor on chloride secretion in human intestinal epithelia.
OBJECTIVE
Transcellular chloride transport is the key event underlying epithelial hydration in the intestine. Little is known about the role of protein tyrosine phosphatases in the regulation of basal and stimulated secretion in human intestinal epithelia. The aim of our study was to investigate the effects of the protein tyrosine phosphatase inhibitor sodium orthovanadate on vectorial chloride transport in native human colon.


METHODS
An electrophysiological technique was used to measure changes in short-circuit current via a dual voltage/current clamp in native human colon mucosa and in T84 (ATCC) human intestinal cells mounted in modified Ussing chambers.


RESULTS
Orthovanadate (1 mM) added to the serosal side of native human colon caused a net rise in short circuit current, reflecting the stimulation of serosal-to-mucosal chloride movement. Epithelial cells responded similarly to the same concentration of the compound. The stimulatory effect of orthovanadate was enhanced by pretreatment with the tyrosine kinase inhibitor genistein, but only when orthovanadate was added to the basolateral chamber. In contrast, the synergistic interaction did not occur when epithelial cells were previously exposed to the cAMP agonist forskolin.


CONCLUSIONS
We show that tyrosine phosphatases may be involved in the regulation of epithelial chloride transport, and that orthovanadate stimulates secretion in the human colon.
Mayol
J
J
Surgery II Service, Hospital Universitario San Carlos, Universidad Complutense, Madrid, Spain. jmayol@hcsc.insalud.es
Alarma-Estrany
P
P
Adame
Y
Y
Alvarez Fernández-Represa
J
J
D002460:Cell Line; D002712:Chlorides / Q000378:metabolism*; D004594:Electrophysiology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors*; D014638:Vanadates / Q000494:pharmacology
D002712:Chlorides; D004791:Enzyme Inhibitors; D014638:Vanadates; D017027:Protein Tyrosine Phosphatases