Cardiac vagal action and plasma levels of neuropeptide Y following intravenous injection in the dog

Abstract

Neuropeptide Y (NPY) is a 36-amino acid peptide found co-localised with catecholamines in many sympathetic postganglionic nerves. Intravenous injection of NPY (6–10 nM/kg) in dogs causes a prolonged attenuation of cardiac vagal action (30–180 min). Peripheral plasma was collected throughout this period of vagal attenuation and plasma NPY levels were measured by radioimmunoassay. The half-life of NPY in peripheral plasma was shown to be approximately 20 min (range 20–28 min). The suggestion is made that the prolonged attenuation of vagal action may be due to high circulating levels of NPY.