The microcirculatory bed of the neurosecretory nuclei was studied post-mortally in three groups of patients with various levels of the functional activity of the hypothalamus-pituitary neurosecretory system (HPNS), namely basal, high and lowered. Sudden death from a heart attack was associated with signs of inhibition in the HPNS cells, edema manifestations in the HPNS zone, by a considerable increase in the number of functionally inactive capillaries, narrowing of their lumina and a decrease in their transport capacities determined by the level of alkaline phosphatase activity in their wall. These changes correlated with an elevation of the number of dark cells in the neurosecretory nuclei which suggests the existence of the functional connection between them.