Role of plasma vasopressin as a mediator of nausea and gastric slow wave dysrhythmias in motion sickness. Kim, Michael S., William D. Chey, Chung Owyang, William L. Hasler. Division of Gastroenterology, Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, MI, 48109
APStracts 3:0234G, 1996.
The possible role of vasopressin in nausea and gastric dysrhythmias in motion sickness was tested by electrogastrography in 14 subjects during circular vection (60o/sec) and vasopressin infusion. Tachygastria was expressed as the signal percent >4.5 cycles/min. Vection evoked nausea scores of 2.6 0.2 (0=none to 3=severe) in 10 subjects with increases in tachygastric activity (15 2 to 45 3%) and plasma vasopressin (4.5 1.5 to 8.4 2.5 pg/ml), that were blocked by atropine but not indomethacin. 4 asymptomatic subjects had no tachygastria or vasopressin release. Vasopressin at 0.2 U/min (plasma level=322.1 10.3 pg/ml) evoked nausea (2.6 0.4) and increases in tachyarrhythmic activity (41 5%) that were blunted by atropine but not indomethacin. There were no differences in nausea or dysrhythmias with vasopressin infusion in subjects who noted nausea during vection versus those who did not. To conclude, vection evokes nausea, dysrhythmias, and vasopressin release in motion sickness -susceptible humans via cholinergic, prostaglandin-independent pathways. Supraphysiologic vasopressin infusions evoke nausea and dysrhythmias by similar pathways to equal degrees in motion sickness -susceptible and resistant subjects. Thus central but not peripheral actions of vasopressin may contribute to nausea and slow wave disruption with vection. Blunting of both the release and action of vasopressin by atropine may explain its beneficial action in motion sickness. 

Received 2 October 1995; accepted in final form 2 October 1995.
APS Manuscript Number G424-5.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 13 November 1996