INVOLVEMENT OF A PERIPHERAL MECHANISM IN THE EMESIS INDUCED BY CARDIAC-GLYCOSIDES IN SUNCUS-MURINUS

The ability of three cardiac glycosides, ouabain, digitonin and digito xin, to induce emesis and their mechanism(s) of action were investigat ed in Suncus murinus. The intraperitoneal injection of ouabain but not digitonin nor digitoxin caused vomiting in a dose-dependent manner. H owever, the administration of ouabain into the cerebroventricle did no t cause emesis. Ouabain-induced emesis was partly prevented by surgica l abdominal vagotomy. Pretreatment with tropisetron, a selective 5-HT3 (5-hydroxytriptamine) receptor antagonist, did not affect the emetic response evoked by ouabain. These results suggest that ouabain exerts emetic effects pia peripheral mechanism(s), but 5-HT3 receptors are no t involved in the pathway.