Renin and inhibitor complex. Computer model showing the secondary structure of the enzyme renin complexed with inhibitor 7. Beta sheets (arrows), alpha helices (coils) and random coils (wires) can be seen. Renin is produced by the kidneys. It is part of the renin-angiotensin-aldosterone pathway that is responsible for controlling blood pressure by balancing sodium and potassium levels in the blood, and fluid levels in the body. Too much renin can cause high blood pressure, therefore various inhibitors have been created to block its action. Inhibitor-7 is one of these.