The protective effect of angiotensin converting enzyme inhibitors and angiotensin II receptor blockers on radiation-related heart disease and radiation-related lung injury

Radiotherapy involving the thorax increases the risk of cardiovascular disease and lung dysfunction. Several studies show that angiotensin converting enzyme (ACE) inhibitor and angiotensin II receptor blocker mitigate the radiation induced injuries. Angiotensin converting enzyme captopril results in a superior mitigation compared to angiotensin II receptor blocker Losartan. Therefore, the protective effect of captopril on heart and lung tissue is the interest of this study. Captopril could act RAAS independent and prevent degradation of the vasodilator and growth inhibitor bradykinin. Besides, captopril is an ACE inhibitor with a thiol group. This side group can act as an antioxidant to reduce inflammatory reactive oxygen species and could play an important role in the superior mitigation of captopril by radiation induced injuries. The protective effect of captopril on heart and lung tissue after radiotherapy can be due to preventing degradation of bradykinin and due to the antioxidant side group.