[Mechanism of emetic action of adrenaline and histamine in the dog].

It has been established in dog experiments that phentolamine prevents the emetic action of adrenaline whereas diphenhydramine the emetic effect of histamine. Both the drugs in the doses studied do not produce any effect on vomiting induced by L-DOPA. The dopamine blockers, etaperazine, haloperidol and metoclopramide given in the doses suppressing the emetic action of L-DOPA do not prevent the adrenaline- and histamine-induced vomiting. It is assumed that the emetic action of adrenaline is effected in dogs via alpha-adrenoreceptors, whereas the histamine-induced vomiting via H1-histamine receptors of the trigger zone of the vomiting center.