title: Influence of the emetic reflex on vasopressin release in man.
abstract: The mechanisms underlying the frequent association of nausea and vomiting with elevations of plasma vasopressin(PAVP) were studied in man and rat. After oral water loads (N = 16), plasma osmolality fell in all human subjects and was associated with a decline in PAVP in 14 asymptomatic human subjects. In 2 human subjects, nausea occurred and was associated with increases in PAVP, without changes in blood pressure. During ethanol infusion (N = 28), PAVP was suppressed unless nausea supervened. In 4 nauseated human subjects, PAVP escaped from ethanol inhibition and rose to levels 10 times basal, despite the absence of hemodynamic changes. Apomorphine, a potent dopamine agonist and emetic agent, was administered to human volunteers in doses of 7 to 24 microgram/kg. There was no increase in PAVP in 3 human subjects who remained asymptomatic (7 to 16 microgram/kg). Ten human subjects experienced nausea after 16 microgram/kg, which was followed shortly by marked increases in PAVP. Emesis occurred in 5 human subjects given 16 to 24 microgram/kg, and was followed by PAVP levels similar to those seen with nausea alone. In 7 human subjects from the nausea group, the repeat study (16 microgram/kg) after pretreatment with dopamine antagonist (haloperidol, N = 4; fluphenazine, N = 3) resulted in complete blockage of apomorphine-induced AVP release. In rats, which lack an emetic reflex, apomorphine doses of 200 microgram/kg induced only slight increases in PAVP when compared to the response to 16 microgram/kg in man. These studies indicate that stimulation of the emetic reflex results in AVP-release in man. Nausea-mediated AVP release supervenes over concomitant osmolar or pharmacologic (ethanol) inhibition.
mesh_terms: D000438:Alcohols; D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D001794:Blood Pressure; D004231:Diuresis; D005260:Female; D006801:Humans; D008297:Male; D009325:Nausea / Q000139:chemically induced; D051381:Rats; D014667:Vasopressins / Q000378:metabolism*; D014839:Vomiting / Q000139:chemically induced / Q000378:metabolism*; D014867:Water
chemical_list: D000438:Alcohols; D014867:Water; D014667:Vasopressins; D001058:Apomorphine