ClC-2 chloride secretion mediates prostaglandin-induced recovery of barrier function in ischemia-injured porcine ileum.
OBJECTIVE
Ischemia results in the breakdown of the intestinal barrier, predisposing patients to sepsis and multiple organ failure. Prostaglandins play a critical role in mediating recovery of barrier function in ischemia-injured intestine through a mechanism involving stimulation of Cl - secretion. In the present study, we investigated the contributory role of individual Cl - channels in the recovery of barrier function in ischemia-injured porcine ileum.


METHODS
Ischemia-injured porcine ileal mucosa was mounted in Ussing chambers. Short-circuit current (Isc) and transepithelial resistance (TER) were measured in response to prostaglandin E 2 (PGE 2 ) and pharmacologic inhibitors of epithelial Cl - channels. Immunoassays were used to assess the expression and localization of ion channels.


RESULTS
Application of PGE 2 to ischemia-injured ileal mucosa stimulated increases in Isc, an indicator of Cl - secretion, that was followed by marked increases in TER, an indicator of barrier function recovery. In vitro studies revealed that although PGE 2 induced Cl - secretion via at least 3 distinct secretory pathways, recovery of barrier function was initiated by Cl - secretion via ClC-2 Cl - channels co-expressed with occludin and localized to tight junctions within restituting epithelium. Intravenous administration of furosemide to pigs subjected to 1 hour of ileal ischemia impaired recovery of barrier function, as evidenced by decreased TER and increased mucosal-to-serosal 3 H-mannitol flux after a 2-hour reperfusion/recovery period, confirming an important role for Cl - secretory pathways in vivo.


CONCLUSIONS
ClC-2-mediated intestinal Cl - secretion restores TER in ischemia-injured intestine. These data may provide the basis for targeted pharmacologic therapy for diseases associated with impaired barrier function.
Moeser
Adam J
AJ
Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, USA.
Haskell
Melissa M
MM
Shifflett
Donnie E
DE
Little
Dianne
D
Schultz
Bruce D
BD
Blikslager
Anthony T
AT
D000818:Animals; D000090007:CLC-2 Chloride Channels; D018118:Chloride Channels / Q000378:metabolism*; D002712:Chlorides / Q000378:metabolism; D015232:Dinoprostone / Q000494:pharmacology*; D017097:Electric Impedance; D005260:Female; D007082:Ileum / Q000098:blood supply*; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology; D007511:Ischemia / Q000378:metabolism* / Q000503:physiopathology; D008297:Male; D023421:Models, Animal; D010539:Permeability / Q000187:drug effects; D011453:Prostaglandins / Q000494:pharmacology*; D020127:Recovery of Function / Q000187:drug effects / Q000502:physiology; D013552:Swine
D000090007:CLC-2 Chloride Channels; D018118:Chloride Channels; D002712:Chlorides; D011453:Prostaglandins; D015232:Dinoprostone