Identification of a specific transport system for L-arginine in human platelets

The present study demonstrates that human platelets possess a specific L-arginine transport system able to provide adequate amounts of L-arginine for endogenous nitric oxide production. L-arginine uptake takes place through a saturable high affinity carrier-mediated Na(+)-independent process which is significantly inhibited by L-ornithine, L-lysine and N omega-methyl-L-arginine. The high affinity of the transport process and the pattern of inhibition are consistent with mediation of L-arginine transport via the Na(+)-independent y+ system. The data on the kinetic parameters of the transporter suggest a possible role for arginine plasma levels in the regulation of platelet nitric oxide production.