Further studies on the effects of ketotifen on guinea pig ileum

Ketotifen (Ke) at the concentration of 10(-5) M or greater significantly inhibits guinea pig ileum contractions induced by cumulative dose response curves to Pg alpha F2 or BaCl2. This inhibitory effect of Ke is also observable against ileal contractions induced by isotonic and hypertonic solutions with high K+ and by electrical stimulation. In contrast to the long term antihistaminic effect of DSCG and Ke, the latter drug exhibits a shorter inhibitory effect when Ach and electrical stimulation are used to induce ileal contractions shortly after Ke is removed by washing from the organ bath. This nonspecific protective effect of Ke on smooth muscle against various spasmogens resembles the one reported recently by us for DSCG and might be relevant to the antiallergic and antiasthmatic properties of both drugs.