AGTR1 and hyperthyroidism: Araujo et al., also showed that oxidative stress has an important role in hyperthyroidism-induced cardiac hypertrophy, and antioxidant agents reduced reactive oxygen species (ROS) and nitric oxide synthase (NOS) isoforms, nitric oxide metabolites, AT1/AT2 and cardiac hypertrophy (Araujo et al., 2008 ▶).