Transport of L-arginine and nitric oxide formation in human platelets.
The results of the present study show that human platelets take up l-arginine by two transport systems which are compatible with the systems y+ and y+L. These Na+independent transporters have been distinguished by treating platelets with N-ethylmaleimide that blocks selectively system y+. System y+, that accounts for 30-40% of the total transport, is characterized by low affinity for l-arginine, is unaffected by l-leucine, is sensitive to changes of membrane potential and to trans-stimulation. The other component of l-arginine transport identified with the system y+L (approximately 60-70% of the total flux) shows high affinity for l-arginine, is insensitive to N-ethylmaleimide treatment, unaffected by changes in membrane potential, sensitive to trans-stimulation and inhibited by l-leucine in the presence of Na+. Moreover a strict correlation between l-arginine transport and nitric oxide (NO) production in whole cells was found. N-ethylmaleimide and l-leucine decreased NO production as well as cGMP elevation, and the effect on NO and cGMP were closely related. It is likely that the l-arginine transport systems y+ and y+L are both involved in supplying substrate for NO production and regulation in human platelets.
Signorello
Maria G
MG
Dipartimento di Medicina Sperimentale, sezione Biochimica, Università di Genova, Italy.
Pascale
Raffaele
R
Leoncini
Giuliana
G
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001120:Arginine / Q000378:metabolism*; D001692:Biological Transport; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D006152:Cyclic GMP / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000378:metabolism; D005033:Ethylmaleimide / Q000378:metabolism; D006096:Gramicidin / Q000494:pharmacology; D006801:Humans; D007476:Ionophores / Q000494:pharmacology; D007930:Leucine / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism; D014634:Valinomycin / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D004791:Enzyme Inhibitors; D007476:Ionophores; D026901:Membrane Transport Proteins; D000644:Quaternary Ammonium Compounds; D006096:Gramicidin; D014634:Valinomycin; D009569:Nitric Oxide; D001120:Arginine; C027435:tetrapentylammonium; D012964:Sodium; D007930:Leucine; D006152:Cyclic GMP; D005033:Ethylmaleimide