Specific Features of Immediate Expression of Succinate-Dependent Receptor GPR91 in Tissues during Hypoxia.

Under normoxic conditions, succinate-dependent receptor GPR91 was found in varying amounts in all analyzed aerobic tissues except erythrocytes. The maximum density of the receptor was observed in the myocardium: by 2.3 and 1.7 times higher than in the kidneys and brain cortex, respectively. Hypoxic expression of GPR91 was tissue-specific, depended on the duration and severity of hypoxia, and did not correlate with the basal level of this receptor. It was maximum in the brain cortex, which confirms the high importance of this signal pathway for brain functioning. Single hypoxic exposure induced immediate expression of GPR91 in the brain cortex within 15-60 min, which correlated with the development of urgent tolerance to hypoxia of the body. Induction of immediate expression of GPR91 in brain cortex occurred during first 15-60 min and correlated to the forming of immediate tolerance of organism to hypoxia. Brain cortex-specific immediate expression of GPR91 during hypoxia was related to activity of the GABA-bypass that acts as the source of succinate for the receptor under these conditions.