GLP1R and hydrops fetalis: In contrast, inhibition of parasympathetic activity with the muscarinic antagonist atropine (Janssen et al.2000; Laude et al.2008; Young & Davisson, 2011) or the GLP-1 receptor agonist Ex-4, which was only recently discovered to affect parasympathetic cardiovascular control (Griffioen et al.2011), caused similar reductions in HF power of HRV in both WT and KO mice.