Abstract
We measured the action of dopamine given intravenously at dosage ranging from 2.5 to 320 micrograms/kg per min in closed chest anaesthetized dogs. Dopamine produced a dose-dependent increase in heart rate, cardiac index, mean arterial pressure, total peripheral resistance, pulmonary artery pressure, left ventricular end diastolic pressure, coronary flow and myocardial oxygen consumption. At dopamine dosage of 80-320 micrograms/kg per min, the coronary vascular resistance, the stroke volume index, the efficiency of heart work and the central venous pressure are all decreased. The maximum effect of dopamine on the circulation was seen at a dose between 40 and 80 micrograms/kg per min.