Pharmacodynamically induced changes in left ventricular work, using an intravenous infusion of Hypertensin, were studied in intact anesthetized dogs. Coronary and systemic hemodynamics and cardiac metabolism under a combined morphine- “Dial” -urethane-pentobarbital-sodium (MDUP) anesthesia were measured during the action of the drug. The significant hemodynamic changes induced were increased mean arterial pressure and increased left ventricular work. A greater cardiac lactate utilization during the Hypertensin infusion was the only change in cardiac metabolism. The oxygen tension in left ventricular venous blood was not reduced during the action of the drug.