HMOX1 and endothelial dysfunction: Thus, in SHR, the chemical induction of HO-1, the administration of its substrates, and HO-1 gene transfer attenuate hypertension, an effect that is repressed by inhibitors of this enzyme (Levere et al., 1990; Sabaawy et al., 2001; Wang et al., 2006; Li et al., 2013) and that has been associated to the improvement of endothelial dysfunction by mechanisms involving EDH-type relaxations (Li et al., 2013).