Autonomic function and plasma catecholamines following stressful sensory stimuli.

This experimentation defined a limited role for epinephrine in the autonomic nervous system function and the nausea that occurred following motion sickness testing. Individual responses to stressful sensory stimuli and nausea, as reflected by rising peripheral levels of epinephrine, were not significantly diminished upon repeated exposure and adaptation to the stressor. However, subjects who demonstrated more robust elevations of epinephrine in response to nausea displayed higher resistances to stressful motion stimuli. Modulation of peripheral catecholaminergic function with dexamethasone, or scopolamine plus amphetamine, suggested that altered autonomic nervous system function and nausea following motion sickness testing were not mediated by peripheral catecholamine receptor stimulation. Marked differences were noted in individual responses to drug and systemic responses of epinephrine and norepinephrine. It is possible that responses in epinephrine to motion sickness testing may predict resistance to stressful motion, and represent a peripheral manifestation of some as yet unknown central event of etiologic relevance.