Unstimulated and amphetamine-stimulated release of endogenous noradrenaline and dopamine from rat brain in vivo.

The in vivo release rates of endogenous noradrenaline from the hypothalamus and dopamine from the caudate nucleus of the rat have been determined. Artificial CSF perfusates collected from a push-pull cannula inserted into specific areas of the brain were assayed for the amines by a sensitive radioenzymatic procedure. The release rates of noradrenaline and dopamine into artificial CSF perfusates were 38 +/- 6 and 46 +/- 6 pg/h (225 +/- 36 and 301 +/- 39 fmol/h), respectively; when 0.5 mM amphetamine was added to the CSF, the release rates of noradrenaline and dopamine increased to 176 +/- 50 and 1183 +/- 453 ph/h (1041 +/- 296 and 7732 +/- 2961 fmol/h), respectively.