Interaction of the cardiovascular risk marker asymmetric dimethylarginine (ADMA) with the human cationic amino acid transporter 1 (CAT1)

► First direct kinetic data of cellular ADMA uptake by CAT1 (SLC7A1) are generated. ► CAT1 can mediate uptake as well as efflux of ADMA. ► The Km value for CAT1-mediated uptake was lower for ADMA than for l-arginine. ► Physiological ADMA levels do not impair CAT1-mediated uptake of l-arginine and SDMA. ► At physiological concentrations, l-arginine inhibits CAT1-mediated uptake of ADMA.