NORADRENALINE AND DOPAMINE INFUSIONS MODULATE ARACHIDONIC-ACID CYCLOOXYGENASE AND 5-LIPOXYGENASE PATHWAYS EX-VIVO IN MAN

We have previously demonstrated that adrenaline infusion increases the thromboxane/leukotriene (TX/LT) ratio in whole blood in healthy volun teers. The aim of the present study was to see whether other catechola mines - noradrenaline and dopamine - are also capable of modulating ar achidonic acid (AA) metabolism in man, Low doses of noradrenaline (0,0 25 mu g/kg/min) and dopamine (3.0 mu/kg/min), which did not change hem odynamics, were infused for 60 min into healthy male volunteers. Both dopamine and noradrenaline decreased TX synthesis stimulated by sponta neous clotting, but no remarkable effect was seen when calcium ionopho re A23187 was used as a stimulus, Dopamine but not noradrenaline incre ased prostaglandin E(2) (PGE(2)) synthesis in A23187-stimulated whole blood, They both marginally decreased LTB(4) formation in A23187-stimu lated whole blood. The findings indicate that not only adrenaline but also noradrenaline and dopamine modulate AA metabolism in man.