[Pro34]neuropeptide Y selectively identifies postjunctional-mediated actions of neuropeptide Y in vivo in rats and dogs.

Anaesthetised rats and dogs were used to study the pre- and postjunctional actions of neuropeptide Y (NPY) and [Pro34]NPY simultaneously. Increases in arterial blood pressure indicated postjunctional actions and both NPY and [Pro34]NPY elicited these. Change in pulse interval evoked by stimulation of the cut peripheral end of the right vagus nerve, indicated prejunctional action of the peptides: NPY caused prolonged attenuation of vagal action in rats and dogs but [Pro34]NPY did not attenuate vagal action in rats or dogs.