[Determination of the role of the hypothalamic lateral mammilar nucleus in regulation of neurons in the respiratory center of rat's medulla during hypoxia].

The pulse activity of medullar respiration center neurons and rat's respiration as a function of excitation of the lateral mammillary (LM) nucleus of the hypothalamus were studied in differing hypoxic conditions. Electrical stimulation of the LM nucleus in normoxia had a predominantly activating effect. A moderate pO2 fall at the start of "ascent" to 4000-5000 m increased pulsation of the respiratory neurons. On this background the activating effect of LM nucleus stimulation was less pronounced as compared to normoxia although it still prevailed over inhibition. The alleviating effect of LM nucleus stimulation was particularly evident with a sharp inhibition of respiratory neurons caused by critical oxygen deficiency at the highest altitude (7500-8000 m). After the "descent" to the normal atmospheric pressure the spontaneous rhythmic activity of rat's neurons and reaction to stimulation gradually recovered baseline values.