In vitro evaluation of intraluminal factors that may alter intestinal permeability in ponies with carbohydrate-induced laminitis

Objectives - To study the in vitro effects of cecal contents incubated with corn starch on colonic permeability in horses. Animals - 4 healthy adult ponies. Procedure - Mucosal specimens were obtained from the right ventral colon an d mounted in Ussing chambers. Changes in short circuit current, conductance , and large-molecule permeability in response to addition of cecal contents and cecal contents incubated with corn starch were evaluated for 120 minut es. Results - Incubation of cecal contents with corn starch for 8 hours resulte d in a decrease in cecal content pH and an increase in lactic acid concentr ation. These changes were similar to those reported in vivo for ponies give n corn starch. Exposure of colonic mucosa to cecal contents incubated with corn starch resulted in an increase in tissue conductance and permeability of technetium Tc 99m pentetate, compared with mucosa exposed to cecal conte nts alone. Conclusions and Clinical Relevance - In vitro exposure of colonic mucosa to cecal contents incubated with starch resulted in increased paracellular pe rmeability. Fermentation of excessive amounts of carbohydrate in the intest inal lumen of horses may directly induce increased intestinal permeability associated with carbohydrate-induced laminitis.