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The autonomic phenotype of congestive cardiac failure is characterised by high sympathetic drive and impaired vagal tone, which are independent predictors of mortality. We hypothesize that impaired bradycardia to peripheral vagal stimulation following high-level sympathetic drive is due to sympatho-vagal crosstalk by the adrenergic co-transmitters galanin and neuropeptide-Y (NPY). Moreover we hypothesize that galanin acts similarly to NPY by reducing vagal acetylcholine release via a receptor mediated, protein kinase-dependent pathway. Prolonged right stellate ganglion stimulation (10Hz, 2min, in the presence of 10μM metoprolol) in an isolated guinea pig atrial preparation with dual autonomic innervation leads to a significant (p<0.05) reduction in the magnitude of vagal bradycardia (5Hz) maintained over the subsequent 20min (n=6). Immunohistochemistry demonstrated the presence of galanin in a small …