IS INHIBITION OF DOPAMINE UPTAKE RELEVANT TO THE HYPNOTIC ACTION OF IV ANESTHETICS

We have examined the effects of ketamine, etomidate, propofol and thio pentone on the uptake of [H-3]-dopamine into rat striatal synaptosomes . [H-3]-dopamine uptake (5 min, 37 degrees C) was potently inhibited b y nomifensine, a classical inhibitor of the dopamine carrier. All anae sthetics induced concentration-related inhibition of the uptake proces s, values for IC50 being 4.6 x 10(-6), 5.5 x 10(-5), 1.5 x 10(-4) and 2.7 x 10(-4) mol litre(-1) for ketamine, etomidate, propofol and thiop entone, respectively. For all anaesthetics, inhibition of [H-3]-dopami ne uptake was reversible with a non-competitive profile. These data su ggest that inhibition of striatal dopamine uptake may represent a rele vant target site for some, bur not all, i.v. anaesthetics.