The Chemoreceptor Trigger Zone for Emesis in the Monkey

Abstract

Intravenous administration of hydergine (90-270 [mu]/kg), and apomorphine (5-15 mg/kg) and subcutaneous injection of apomorphine (25-100 mg/kg) failed to produce an emetic response in normal monkeys. Intravenous administration of lanatoside C in doses of 0.1-0.24 mg/kg failed to produce emesis but a lethal dose (0.3 mg/kg) resulted in passive emission of stomach contents in 1 animal. Exposure to X-irradiation resulted in emesis in 4 intact animals at 800 r and 5 at 1200 r although 1 animal tested at 1000 r failed to vomit. Following ablation of the chemoreceptor trigger zone for emesis by cautery, exposure to 1200 r X-irradiation failed to elicit an emetic response in 13 of 14 operated animals. It is concluded that the chemoreceptor trigger zone for emesis in the monkey is virtually nonfunctional from the standpoint of drug action. The problem of the locus of emetic action of X-irradiation is discussed in terms of the chemoreceptor trigger zone for emesis and the dorsal sensory vagal nucleus.