[Leu 31, Pro 34] NPY, a selective functional postjunctional agonist at neuropeptide-Y receptors in anaesthetised rats

Neuropeptide Y (NPY), a sympathetic cotransmitter, has both prejunctional and postjunctional actions in the cardiovascular system. In the bioassay system used here NPY attenuates cardiac vagal action (an indicator of prejunctional or Y 2 action) and increases blood pressure (an indicator of postjunctional or Y 1 action). [Leu 31,Pro 34]NPY has little or no prejunctional activity i.e does not attenuate cardiac vagal action, but increases blood pressure as effectively as NPY. [Leu 31,Pro 34]NPY can therefore be used in functional experiments to distinguish between the two types of NPY receptor.