Neuropeptide Y (NPY) reduces myocardial perfusion and inhibits the force of contraction of the isolated perfused rabbit heart

Isolated rabbit hearts, perfused under constant pressure (Langendorff technique) were used to study the effect of neuropeptide Y (NPY) on heart rate, force of heart contraction and rate of myocardial perfusion. No significant net change in heart rate was noted. A dose-dependent negative inotropic effect was consistently demonstrated which was characterised by slow onset and was often preceded by a transient positive inotropic response. Addition of small doses of NPY resulted in a prompt reduction in flow of the perfusate through the coronary vasculature. Since NPY is present locally in cardiac nerves, these effects may have physiological importance.