In vivo electrochemical monitoring of apomorphine penetration into the rat brain.

Differential normal pulse voltammetry was used together with electrochemically treated carbon-fibre electrodes to monitor apomorphine (APO) penetration into the cortex of anaesthetized rats after a peripheral administration of this drug. In vivo cortical APO extracellular concentration and post-mortem APO levels both measured by means of this technique were estimated to be, respectively, 105 +/- 8 nM and 14.6 +/- 1.1 nmol/g of tissue. The maximal extracellular concentration was reached 16 min after a s.c. injection and reached a plateau beyond a dose of 4 mg/kg (s.c.). This suggests that APO is mainly trapped within brain cells.