Regulatory Mechanism of Cationic Amino Acid Transporters in Hepatic Sinusoidal Ito Cells

Abstract

Nitric oxide (NO) is a potent mediator of hepatic sinusoidal hemodynamics. It is synthesized in and affects hepatic Ito cells. Although NO production may depend on the induction of inducible nitric oxide synthase (iNOS) and on transport of extracellular L-arginine, the precise mechanism controlling NO production in stellate cells has not been well characterized. Recently, however, the L-arginine transport system functioning in transformed hepatic stellate cells was identified. In this review, we show the regulatory mechanisms involved in system y+, which may be mediated by cationic amino acid transporter-1 (CAT-1) and CAT-2B during uptake of extracellular L-arginine as the substrate for NO synthesis.