In a further study, the same group showed a positive impact of renin-angiotensin system blockade with an AT1-blocker, losartan, in the autonomic control of heart rate which was coupled with a decline in H2O2 levels, as well as with a decreased counterregulatory response of heme-oxygenase-1, and cardiac hypertrophy in experimental hyperthyroidism [66]. Here, REN is linked to cardiac hypertrophy.