NPPA and cyclic hematopoiesis: Despite observed increases in circulating ANP, CH‐PH did not increase cGMP levels in the lung (993 ± 502 pmol/mg vs 667 ± 210 pmol/mg; p = 0.27) or RV (47 ± 18 pmol/mg vs 49 ± 13 pmol/mg; p = 0.88) tissue (Figure 3a).