The human gene SLC22A3 encodes organic cation transporter OCT3. It is mainly expressed in skeletal muscle, liver, placenta, kidney and heart, and to a lesser extent in brain. OCT3 is involved in the biliary excretion of cationic drugs. In CNS, ganglia and heart, OCT3 regulates the interstitial concentrations of monoamine neurotransmitters and cationic drugs. In placenta, OCT3 is responsible for the release of acetylcholine during nonneuronal cholinergic regulation (Grundemann D et al,1998; Wu X et al, 2000).