Ion transport abnormalities in inflamed rat jejunum. Involvement of mast cells and nerves

Basal and stimulated changes in ion transport in vitro were examined in jejunal mucosa from rats during inflammation produced after infection with the nematode Nippostrongylus brasiliensis. The gut was acutely inflamed at days 7 and 10 when net secretion of Na⁺ and Cl^- ions was evident. Serum levels of rat mast cell protease II were elevated, providing evidence for mast cell activation. In addition, the magnitude of the short-circuit current responses to electrical transmural stimulation of enteric nerves (but not to histamine in the presence of neural blockade) were significantly reduced (p < 0.01) to 17%-33% of control values, suggesting abnormalities of mucosal nerves. Following worm expulsion, serum levels of rat mast cell protease II and ion transport returned to normal. However, mastocytosis was apparent in gut mucosa and parasite antigen stimulated net secretion. In the absence of antigen, short-circuit current responses to nerve stimulation were increased (to 122% of controls; p < 0.05). These findings suggest that changes in mast cells and enteric nerves occur during inflammation in this model and implicate neural and mast cell interactions with the epithelium in producing the ion-transport abnormalities.