ETIOLOGIC SIGNIFICANCE OF ARGININE-VASOPRESSIN IN MOTION SICKNESS

There is abundant-evidence implicating the role of arginine vasopressi n in motion sickness. The effects of AVP analogs on motion sickness we re investigated in squirrel monkeys. Two specific V-1 antagonists (SK& F 100273 and SK&F 103561) and three mixed V-1/V-2 antagonists (SK&F 10 1926, SK&F 105494, and SK&F 104146-D) were tested on six highly suscep tible monkeys. Intravenous injections of 200 ug of a v, antagonist abo lished emesis in all six monkeys, and few prodromal symptoms remained (latency to emesis > 120 minutes, P < .001). Mixed V-1/V-2 antagonists foiled to abolish emesis in all monkeys. However, there was a slight increase in the latency to the first bout of emesis/retching with the mixed antagonists when compared with the baseline. The dose-response r elationship and rate of onset of action of the V-1 antagonists (SK&F 1 00273) were explored. Latency to the first bout of emesis/retching inc reased to about twice that of the baseline when half of the effective antiemetic dose was used. The efficacy demonstrated by the specific V- 1 antagonists indicates that V-1 receptors may modulate emesis.