To ascertain the mechanisms of the locus coeruleus (LC) function the response of the locus coeruleus neurons to the experimental sharp asphyxia was investigated by the light and electron microscope techniques. Apart from the specific nervous effect (directly through the LC axons and through the stem reticular formation), LC produced humoral influence on the brain structures. There are two possible mechanisms by which catecholamines synthesized in the LC cells could reach the blood; 1) through the cell membrane and then through the basal membrane of the capillary bed and the cytoplasm of the endothelial cell; 2) by virtue of the glia cells.