EFFECTS OF LONG-TERM SENNOSIDE TREATMENT ON IN-VITRO MOTILITY OF RAT COLON

Colonic motility of rats chronically pretreated with either 10 or 40 m g sennosides/kg body weight daily, 30 mg sennosides/kg twice a week or 500 mg danthron/kg daily for 6 months has been evaluated in ex vivo p reparations. Registration of colonic contractions 48 h after the last application of drugs or placebo revealed striking differences between the ascending, transverse and descending parts of the colon as well as between corresponding circularly or longitudinally orientated segment s. Treatment did not influence motility in the various parts of the co lon except some reduction in spontaneous motility in the descending co lon. Response to electrical stimulation and acetylcholine was independ ent of treatment in most segments, but a decrease in maximal contracti on was observed by the high daily sennoside dose and by danthron in th e ascending colon and descending colon, respectively. Sensitivity to r hein, an active metabolite of sennosides, was similar in all groups. T hus, chronic treatment with anthranoids reveals no abnormal motility p attern but a residual pharmacological activity 48 h after the last adm inistration of high doses.