Myocardial power output of an isolated eel (Anguilla dieffenbachii) heart preparation in response to adrenaline

1. Myocardial power output was continuously monitored in an isolated perfused eel heart. Maximum cardiac power output and the conditions (e.g. filling and output pressures, cardiac outputs) under which maximum power occurred were determined at 1, 10, 100 and 1000 nmol 1-1 adrenaline. 2. Maximum cardiac power output occurred when the heart pumped high flows against moderate afterload pressures. 3. Adrenaline increased the myocardial power output of the eel heart at lower concentrations by elevating cardiac output via increases in stroke volume, and then at greater adrenaline concentrations by allowing the heart to pump against higher output pressures and by elevating cardiac output via increases in heart rate