One possibility is that the species difference contributes to these inconsistent results during WD, the presence and activation of inhibitory factors, such as bradykinin (Itoh et al., 2014), SPAK isoforms (Grimm et al., 2012; Park et al., 2013), and PGE2 (Itoh et al., 2014), in the normal SD rats but not mice during WD or AVP infusion. This evidence concerns the gene AVP and Wilson disease.