ROLE OF GASTROINTESTINAL INNERVATION IN DIGITALIS EMESIS

¹ Department of Pharmacology, University of Utah College of Medicine, Salt Lake City

Cats were tested chronically for emetic responsiveness to lanatoside C and scillaren A given orally after bilateral ablation of the medullary emetic chemoreceptor trigger zone (CT zone), after gut denervation by vagotomy and sympathectomy, and after a combination of both operations. It was found that, whereas CT-zone ablation abolished the "early" phase of vomiting which follows intravenous glycoside, "late" vomiting was still elicitable after the oral route of administration. There was no apparent change in the vomiting response to oral digitalis in gut denervated cats as compared with normal cats. The adequacy of gut denervation was confirmed by the marked refractoriness to vomiting elicitable by oral CuSO₄. Results with oral glycosides after CT-zone ablation alone or combined with gut denervation indicate that the drugs exert a central emetic effect which summates with that of peripheral emetic stimulation. It is concluded that the emesis induced by orally administered cardiac glycosides is initiated largely by stimulation of peripheral receptors which lie outside of the gastrointestinal tract.