GRK2 and hydrops fetalis: In addition, both treatments can downregulate the HF-related SNS overactivity, attenuating adrenal GRK2 overexpression, increasing adrenal α2 adrenergic receptor density, and finally reducing CA secretion from the adrenal medulla (Rengo et al., 2010, 2012a, 2013; Femminella et al., 2013).