The Concentration of Adrenaline in Human Plasma and its Relation to Mental Activity

It is generally accepted that situations of danger, stress or emergency lead to an increased activity of the sympathetic system and to the discharge of adrenaline from the adrenal medulla. Until recently our knowledge was based, essentially, upon two lines of evidence; on the observation of effector organs and mechanisms, such as heart rate, blood pressure, width of skin capillaries, etc., and on the measurement of the adrenaline concentration in the suprarenals or the suprarenal veins, which contain comparatively large quantities. Lately, with the advent of more refined techniques, further methods have become available, which made it possible to estimate adrenaline in tissues other than the suprarenals, in urine and in peripheral blood. The last two methods are obviously of special importance for clinical studies. In this paper work done in the writer's laboratory will be briefly reviewed. The first part deals with the development of a method for the estimation of adrenaline and noradrenaline in plasma and with experiments that were intended to establish the validity of the method. The concentration of adrenaline and noradrenaline, and the form of their occurrence, in plasma and CSF, will be discussed. In the second part results will be described, which suggest that there is a correlation of the blood-adrenaline level with mental activity.