Pressure-flow relationships in the peripheral circulation of the dog with isoprenaline

1. The effects of isoprenaline on the pressure-flow relationships in the peripheral circulation were studied in five anaesthetized dogs during right heart bypass procedures. 2. Isoprenaline (1 mug/kg per min) produced a significant drop in arterial pressure and arterial resistance. 3. There was a significant decrease in the resistance to venous return which resulted in a significant increase in venous return. 4. The findings suggest that the increase in cardiac output produced by isoprenaline results in large part from dilatation of venous resistance vessels.