We (Huang et al., 2018) and others (Schmid, 1972; Kishimoto et al., 1973; Kopp et al., 1984; Bloomfield et al., 1997; Doty et al., 1999) have demonstrated that renal venous congestion is associated with activation of the renin–angiotensin system (RAS). This evidence concerns the gene REN and hyperemia.