Abstract
Plasma levels of physiological amine metabolites are rarely reported because of the technical difficulties in their measurement. The authors measured plasma levels of both physiological amines and their main matebolites in 14 patients with subarachnoid hemorrhage, using a simplified method of high-performance liquid chromatography employing electrochemical detection, devised by one of the authors (A.M.). Sequential measurements were made during the acute stage (generally, for a 2-week period). The amines and their main metabolites assayed were norepinephrine (NE), epinephrine (EN), dopamine (DA), 3-methoxy-4-hydroxyphenyl glycol (MHPG), 3-methoxy-4-hydroxyphenyl acetic acid (HVA), 3, 4-hydroxyphenyl acetic acid (DOPAC), and 5-hydroxyindole-3-acetic acid (5-HIAA). Five patients were seriously ill and nine were not seriously ill. In the seriously ill group the average maximum concentrations were as follows: NE, 550.4±303.4 pg/ml; EN, 672.4±567.6 pg/ml; DA, 119.8±83.2 pg/ml; MHPG, 17.3±6.2 ng/ml; DOPAC, 2.0±1.9 ng/ml; HVA, 33.3 ± 23.0 ng/ml; and 5-HIAA, 11.2±8.0 ng/ml. In the group not seriously ill the averages were as follows: NE, 764.0±550.4 pg/ml; EN, 1, 258.7± 2, 199.8 pg/ml; DA, 122.4±91.1 pg/ml; MHPG, 7.5±2.6 ng/ml; DOPAC, 4.9±7.5 ng/ml; HVA, 17.2±9.0 ng/ml; and 5-HIAA, 12.4± 9.0 ng/ml. The only significant difference between the two groups was in plasma MHPG, a major metabolite of brain NE, which is highly concentrated in the hypothalamus. Therefore, its marked elevation in plasma in the seriously ill group, and the lack of a significant correlation with plasma NE, may reflect accelerated metabolism of NE in the brain and possibly in the hypothalamus. Thus, measurement of plasma MHPG may be of use in studying the role of the hypothalamus in cerebral angiospasm in subarachnoid hemorrhage. Although there was no significant difference in HVA levels between the two groups, its elevation in plasma coincided with deterioration of the consciousness level in the group who were not seriously ill.
