Activation of the Angiotensin Converting Enzyme Significantly Contributes to Oxidative Stress in the Aorta of Rats with Alloxan-Induced Diabetes

Changes in the activity of the angiotensin converting enzyme and the production of reactive oxygen species in the rat aorta during diabetes induction by alloxan have been studied. The activity of the angiotensin converting enzyme in the aortic segments was determined by the hydrolysis of hippuryl-L-histidyl-L-leucine, and the formation of reactive oxygen species was determined by the oxidation of dichlorodihydrofluorescein. It has been shown that the activity of the angiotensin converting enzyme increases with an increase in blood glucose concentration to a maximum value at a glucose concentration of 12 mM and does not increase with a further increase in glucose levels. In contrast to the activity of the angiotensin converting enzyme, the formation of reactive oxygen species increases with increasing glucose concentration over the entire studied concentration range (up to 24 mM). Experiments with enalapril, an angiotensin converting enzyme inhibitor, have shown that it completely prevents an increase in the rate of formation of reactive oxygen species up to glucose concentration of 12 mM (100% contribution of activation of angiotensin converting enzyme to an increase in the formation of reactive oxygen species), but further the effectiveness of enalapril decreases (about 30% contribution of activation of angiotensin converting enzyme to an increase in formation of reactive oxygen species).

reactive oxygen species, aorta, alloxan, angiotensin-converting enzyme, diabetes, enalapril