NPPA and cyclic hematopoiesis: Atrial natriuretic peptide (ANP) overexpression is protective in the mouse model of chronic hypoxic pulmonary hypertension (CH‐PH) (Klinger et al., 1993), while ANP knockout mice develop more severe CH‐PH (Chen et al., 2006; Klinger et al., 1999; Sun et al., 2000).