THE NONSPECIFIC INDUCTION OF MASTOCYTOSIS IN RAT INTESTINAL MUSCLE

We examined the effects of bowel manipulation on mast-cell number and function in the rat. Mast cells were assessed histologically and by th eir ability to induce muscle contraction. Anaesthesia or abdominal inc ision did not alter mast-cell number. However, laparotomy plus brief e xteriorization of jejunal segments significantly increased mast-cell n umber. Applying saline to the serosal surface by swab or droplet appli cation increased mast-cell number 16- and 3-fold, respectively. Saline swabbing of jejunal segments from rats previously infected with Trich inella significantly reduced mast-cell number. Functional integrity of mast cells was illustrated by muscle contraction in vitro following c ompound 48/80 or antigen and inhibition of cromoglycate. Serosal appli cation of compound 48/80 in vivo increased mast-cell number. This incr ease in mast-cell number by compound 48180 or by saline was prevented by prior treatment with cromoglycate. These data suggest that mast-cel l degranulation underlies the manipulation-induced mastocytosis in gut muscle.