Neuropeptide Y is a prejunctional inhibitor of vagal but not sympathetic inotropic responses in guinea-pig isolated left atria

摘要

1. The effects of NPY and related peptides were examined on basal contractile force and nerve- mediated inotroic responses to electrical field stimulation of the guinea-pig isolated left atrium. 2. Electrical field stimulus (EFS)-Inotroic response curveswere constructed by applying 1-64 trains OF FOUR FIELD PULSES (200 Hz, 0.1 ms duration, 100 V) across isolated left atria (paced at 4 Hz, 2 ms, 1-4V) within the atrial refractory period. Curves were constructed in presence of vehicle, propranolol (1 μM) or atropine (1 uM) to determine appropriate stimulus conditions.