Control of radiation-induced pneumopathy and lung fibrosis by angiotensin-converting enzyme inhibitors and an angiotensin II type 1 receptor blocker

Abstract

ACE inhibitors and one AII type 1 receptor blocker were effective in protecting lungs from radiation-induced pneumonitis and the development of lung fibrosis in two models of rat radiation injury. In the first series of experiments (unilateral irradiation), those ACE inhibitors containing a sulphydryl radical were more effective than those without it. This observation led to the question of whether this protective effect is related to inhibition of AII synthesis or rather to some of the collateral pharmacologic properties of these drugs, such as anti-oxidation or protease inhibition. The AII receptor blocker, however, was shown to be equally effective, if not better, in its antifibrotic capacity than any ACE inhibitor with or without an SH radical, reaffirming the role of AII in modulation of collagen synthesis.