Induction of NG-monomethyl-L-arginine uptake: a mechanism for differential inhibition of NO synthases?
The properties, selectivity, and regulation of NG-monomethyl-L-arginine (L-NMMA) uptake were examined in a human cultured vascular endothelial cell line SGHEC-7 and murine macrophage J774 cells. In both cell types the uptake of L-[14C]NMMA was time and temperature dependent. In endothelial cells L-[14C]NMMA uptake occurred via a single saturable carrier-mediated system with an apparent Kt of 77 +/- 2 microM. In murine macrophage cells a saturable component with an apparent Kt of 51 +/- 6 microM and a nonsaturable component of L-NMMA uptake were identified. In both cell types uptake of L-[14C]NMMA (10 microM) was significantly inhibited in the presence of 100-fold excess of L-NMMA, asymmetric NG,NG-dimethyl-L-arginine (ADMA), symmetric NG,NG-dimethyl-L-arginine (SDMA), L-canavanine, L-arginine, and to a lesser extent D-arginine. Uptake of L-[14C]NMMA was inhibited weakly (approximately 30%) by NG-nitro-L-arginine, NG-nitro-L-arginine methyl ester, aminoguanidine, and L-citrulline. Incubation of macrophage J774 cells with lipopolysaccharide (LPS; 1 or 10 micrograms/ml) resulted in the induction of nitric oxide (NO) synthase activity determined by the accumulation of nitrite in the culture medium. In these cells an enhanced uptake of L-NMMA uptake was observed which was prevented by pretreatment with cycloheximide (1 microM) but not dexamethasone (1 microM).(ABSTRACT TRUNCATED AT 250 WORDS)
Bogle
R G
RG
Department of Pharmacology, St. George's Hospital Medical School, London, United Kingdom.
MacAllister
R J
RJ
Whitley
G S
GS
Vallance
P
P
D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000493:pharmacokinetics; D001692:Biological Transport; D002460:Cell Line; D002956:Citrulline / Q000378:metabolism; D016207:Cytokines / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism; D004731:Endotoxins / Q000494:pharmacology; D006801:Humans; D007700:Kinetics; D008264:Macrophages / Q000378:metabolism; D051379:Mice; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors*; D013997:Time Factors; D019323:omega-N-Methylarginine
D016207:Cytokines; D004731:Endotoxins; D019323:omega-N-Methylarginine; D002956:Citrulline; D001120:Arginine; D019001:Nitric Oxide Synthase