NPPA and hydrops fetalis: In line with earlier onset of HF, as evidenced by reduced CO, in male C57Bl/6 and female Balb/c TAC mice, as compared with female C57Bl/6 (see Supplementary material online, Tables S1–S3), analyses of cardiac expression of ANP and BNP genes (Nppa and Nppb, respectively), used as indicators of cardiac wall stress,19,20 similarly revealed an earlier and more robust increase post-TAC in the first two groups (see Supplementary material online, Figure S1c and e).