Transport of L-[3H]arginine in cultured neurons: characteristics and inhibition by nitric oxide synthase inhibitors.
To investigate whether transport of L-arginine into neurons plays an integral role in the metabolism of the novel neuromodulator nitric oxide, the uptake of L-[3H]arginine was characterized in cultured neurons of mouse cerebellum and cerebral cortex (neocortex). The transport of L-[3H]arginine was saturable and monophasic into both types of neurons with an apparent Km of 100 microM and Vmax of 2.6 nmol/min/mg of protein. The transport process was stereospecific, and the pattern of inhibition by basic L-amino acids was consistent with a "y+" transport system. The potencies with regard to inhibition of L-arginine uptake of the two inhibitors of nitric oxide synthase, NG-monomethyl-L-arginine and NG-amino-L-arginine (IC50 values of 120 and 65 microM, respectively), suggest that these nitric oxide synthase inhibitors may also reduce formation of nitric oxide and cyclic GMP via a block of arginine uptake. Overall, these data indicate that uptake of L-arginine could regulate its intracellular concentration and, consequently, its availability for synthesis of nitric oxide.
Westergaard
N
N
PharmaBiotec Research Center, Department of Biological Sciences, Royal Danish School of Pharmacy, Copenhagen, Denmark.
Beart
P M
PM
Schousboe
A
A
D000594:Amino Acid Oxidoreductases / Q000037:antagonists & inhibitors*; D000596:Amino Acids / Q000494:pharmacology; D000818:Animals; D001120:Arginine / Q000378:metabolism*; D001692:Biological Transport; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000378:metabolism; D002540:Cerebral Cortex / Q000166:cytology / Q000378:metabolism; D006098:Granulocytes / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D019001:Nitric Oxide Synthase; D014316:Tritium
D000596:Amino Acids; D014316:Tritium; D001120:Arginine; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases