Are the effects of noradrenaline, adrenaline and dopamine infusions on$\dot VO_2$ and metabolism transient?and metabolism transient?

Abstract

Objective

To determine whether noradrenaline, adrenaline and dopamine have persistent on$\dot VO_2$ and metabolism.

Design

Descriptive laboratory investigation.

Setting

Laboratory of the Department of Anaesthesiology at a University Hospital.

Subjects

9 volunteers.

Intervention

$\dot VO_2$ and the plasma concentration of glucose and free fatty acids were measured prior to and during a 4 h infusion of saline (control), noradrenaline (0.14 μg/kg min) adrenaline (0.08 μg/kg min) or dopamine (7 μg/kg min),n=9 each.$\dot VO_2$ was measured using an open circuit gas exchange system.

Measurements and main results

$\dot VO_2$ increased from 250±22 ml/min to 280±38 ml/min during noradrenaline, to 298±30 ml/min during adrenaline and to 292±39 ml/min during dopamine infusion. The plasma glucose concentration increased from 6.2±0.6 mmol/l to 8.8±0.8 mmol/l, 13.2±1.4 and 7.3±0.4 mmol/l during infusion of noradrenaline, adrenaline or dopamine, respectively. The plasma free fatty acid concentration increased from 0.28±0.10 mmol/l to 0.79±0.21 mmol/l during noradrenaline and to 0.52±0.09 mmol/l during dopamine. In contrast, free fatty acid values averaged baseline values at the end of the adrenaline infusion after an initial increase to 0.72±0.31 mmol/l.

Conclusions

Administration of noradrenaline, adrenaline or dopamine resulted in persistent increases in$\dot VO_2$ in volunteers. With the exception of the transient adrenaline effect on fatty acids the metabolic actions were steady during 4 h of adrenergic stimulation. Since the adrenergic effect on$\dot VO_2$ is persistent over time a similar action in patients (e.g. septic shock) during treatment with adrenoceptor agonists may be important. Thus, an increase in$\dot VO_2$ during therapy may not only reflect an oxygen debt but also a pharmacodynamic action of adrenoceptor mediated calorigenic and metabolic induction.