Effect of oxidation on the activity of angiotensin converting enzyme in the rat kidney, heart and brain.

The activities of angiotensin converting enzyme (ACE) in crude extracts of renal cortex, heart and brain of the rat were increased when the oxidizing agent diamide was added to the extracts and then the activity determined. By pretreatment of the extracts with 10 mM diamide, the activities of ACE in the extracts of heart, brain and renal cortex were about 500, 290 and 240% of the control value, determined without the diamide-pretreatment, respectively. In the lung and aorta, increments in the activity after oxidation were less than 20% of the control. No such increase was observed in the plasma. Similar results were obtained when the extracts were exposed to O2. The activity was also increased by oxidation with diamide and O2, when an extract of the human renal cortex was used. Thus, the activity of ACE in the kidney, heart and brain can be increased by oxidation.