Alteration of intestinal myoelectrical activity is a characteristic feature of food protein-induced intestinal anaphylaxis in the conscious rat. The motility changes induced by antigen challenge were appraised in egg-albumin-sensitized rats, chronically implanted with NiCr electrodes in the duodenojejunal wall. Intraduodenal infusion of egg albumin given to fasted sensitized rats triggered a disruption of the cyclic pattern of small intestinal motility lasting 79.1 +/- 23.3 min. The duration of the challenge effect on intestinal myoelectrical activity was significantly reduced by systemic capsaicin pretreatment (125 mg/kg) but to a lesser extent by perivagal capsaicin. Substance P (SP) antagonists (SP 4-11 and CP 96.345) and atropine were also able to shorten the duration of the antigen-challenge-induced alteration of intestinal motility. It is concluded that SP and capsaicin-sensitive afferent nerve endings play an important role in the intestinal anaphylaxis-induced disturbances of intestinal motility.