The effects of dopamine, dobutamine, mmrinone and milrinone on cardiopulmonary function were evaluated in isoflurane-anesthetized dogs. Each drug induced the increase in cardiac output dose dependently, and the degree of increase at same dose level (low, middle, high) was almost equivalent. Dopamine and dobutamine increased heart rate and myocardial oxygen consumption dose dependently. Dopamine increased arterial pressure at high dose, while dobutamine did not change on arterial pressure and tended to decrease pulmonary vascular resistance dose dependently. Amrinone and milrinone decreased arterial pressure, systemic vascular resistance and pulmonary vascular resistance, and increased heart rate at high dose without increase of myocardial oxygen consumption.
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