[Content of biogenic amines and their precursors in human blood during head-down tilt and in taking pharmacological agents to prevent the motion sickness syndrome].

The 6-hour exposure to head-down tilt at --15 degrees was accompanied by an increased blood content of adrenaline and noradrenaline, thus indicating the activation of the sympathoadrenal system. The catecholamine concentration was shown to be proportional to the head-down tilt time. The exposure also led to an increase of the content of serotonin and left the content of 5-hydroxytryptophan, tryptophan, histamine and histidine unchanged. After administration of ephedrine and especially, ephedrine in combination with pipolphen the increase in the concentration of catecholamines and serotonin became significantly less pronounced.