ADORA2A and hydrops fetalis: Specifically, our studies over the past few years have established that adrenal GRK2 upregulation is responsible for severe adrenal α2AR dysfunction in chronic HF, which causes a loss of the sympathoinhibitory function of these receptors in the adrenal gland, and catecholamine secretion is thus chronically elevated (Figure 2; Lymperopoulos et al., 2007, 2008, 2010; Rengo et al., 2010, 2012b).