INVOLVEMENT OF NO-SYNTHASE IN THE INFARCT REDUCING EFFECT OF CONTINUOUS CHRONIC NORMOBARTC HYPOXTA

It was investigated the role of inducible and endothelial NO-synthase (NOS) in the infaret reducing effect of chronic continuous normobaric hypoxia (CCNH) on the model of coronary artery occlusion and reperfusion in rats. Rats were subjected to hypoxic exposure (12% O2 during 21 days). It has found that CCNH causes an increase in total levels of nitrate and nitrite in deproteinized blood serum in 1.5-fold and 2-fold in myocardium compared with intact animals. This effect is manifested in intact animals and in rats with a 20 minute coronary artery occlusion and reperfusi- on. Chronic continuous normobaric hvoxia exhibited infarct soaring effect. which does not manifest after pretreatment with NO-synthase inhibitor NAME (10 mg/kg intravenously), the selective inhibitor of inducible NOS S-methylisothiourea (3 mg/kg intraperitoneally), but remained after blocking neuronal NOS with 7-nitronidazol (50 mg/kg intravenously). The findings suggest that the inducible NO-synthase and nitric oxide play an important role in the implementation of the infaret limiting effect of chronic continuous normobaric hvnoxia.