Opposite effects of neuropeptide Y (NPY) and polypeptide YY (PYY) on plasma immunoreactive atrial natriuretic factor...

Female Sprague-Dawley rats were administered NPY and PYY in doses of 0.1, 2.5 or 5, and 10 micrograms in order to determine whether the natriuretic action is the result of increased ANF secretion. NPY injection increased significantly IR-ANF while PYY decreased IR-ANF in the dose-response manner in normally-hydrated rats as well as in water-loaded rats. Opposite effects on plasma IR-ANF were exerted by NPY and PYY, indicating that an increase of ANF release may be responsible for NPY-induced natriuresis.