Extraneuronal Monoamine Transporter and Organic Cation Transporters 1 and 2: A Review of Transport Efficiency

摘要: The extraneuronal monoamine transporter (EMT) corresponds to the classical steroid-sensitivemonoamine transportmechanism that was first described as “uptake2” in rat heart with noradrenaline substrate. organic cation transporters OCT1 and OCT2 are related EMT. three carriers share basic structural functional characteristics. Hence, EMT, constitute a group referred non-neuronal or transporters. After brief general introduction, this review focuses on critical analysis of substrate specificity. We calculate from available literature compare consensus transport efficiency (clearance) data for human OCT2, expressed transfected cell lines. From plethora inhibitors have been tested, casual observer likely gets impression these indiscriminately very many compounds. However, our knowledge about actual substrates is rather limited. 1-Methyl-4-phenylpyridinium (MPP+) an excellent all carriers, clearances typically range 20-50 μl min−1 mg protein−1. secondbest tyramine (TE) relative MPP+ 20%–70%. TEs dopamine, noradrenaline, adrenaline 5-HT low, 5%–15%. This suggests not primarily dedicated transmitters; only EMT may play significant role catecholamine inactivation. Formany substrates, such tetraethylammonium, histamine, agmatine, guanidine, cimetidine, creatinine, choline acetylcholine, efficiencies markedly different among carriers.