SLC9A1 and heart disorder: NHE1 activity is controlled by pHi and numerous other factors, such as hormones, catecholamines, enzymes, and mechanical stimuli, known to be associated with heart disease (Avkiran and Haworth, 2003; Cingolani et al., 2008; Villa-Abrille et al., 2010; De Giusti et al., 2011).