EFFECTS OF NORADRENALINE AND DOPAMINE INFUSIONS ON ARACHIDONIC-ACID METABOLISM IN MAN

We infused noradrenaline (0.025 mu g/kg/min for 60 min, n=7) and dopamine (3.0. mu g/kg/min for 60 min, n=6) into healthy male volunteers to study the effects of these catecholamines on in vivo thromboxane A(2), prostacyclin and leukotriene E(4) production measured as urinary excretions of 11-dehydro-thromboxane (TX) B-2, 2,3-dinor-6-keto-prostaglandin (PG) F-1 alpha and leukotriene (LT) E(4), respectively. Plasma noradrenaline and dopamine concentrations were 2.9+/-0.3 and 233+/-17 nmol/l at the end of the noradrenaline and dopamine infusions, respectively. Noradrenaline decreased thromboxane production and increased leukotriene production almost twofold. It had hardly any effect on prostacyclin production. Dopamine had no significant effects on any of the variables, however it had a tendency to increase prostacyclin and leukotriene production. The results indicate that noradrenaline is a more important modulator of arachidonic acid metabolism than dopamine in vivo.