Activation of L-arginine transport by protein kinase C in rabbit, rat and mouse alveolar macrophages.
1. The role of protein kinase C in controlling L-arginine transport in alveolar macrophages was investigated. 2. L-[3H]Arginine uptake in rabbit alveolar macrophages declined by 80 % after 20 h in culture. 4beta-Phorbol 12-myristate 13-acetate (PMA), but not 4alpha-phorbol 12-myristate 13-acetate (alpha-PMA), present during 20 h culture, enhanced L-[3H]arginine uptake more than 10-fold. Staurosporine and chelerythrine opposed this effect. 3. L-[3H]Arginine uptake was saturable and blockable by L-lysine. After PMA treatment Vmax was increased more than 5-fold and Km was reduced from 0.65 to 0.32 mM. 4. Time course experiments showed that PMA increased L-[3H]arginine uptake almost maximally within 2 h. This short-term effect was not affected by cycloheximide or actinomycin D. 5. L-[3H]Arginine uptake and its stimulation by PMA was also observed in sodium-free medium. 6. L-Leucine (0.1 mM) inhibited L-[3H]arginine uptake by 50 % in sodium-containing medium, but not in sodium-free medium. At 1 mM, L-leucine caused significant inhibition in sodium-free medium also. L-Leucine showed similar effects on PMA-treated cells. 7. N-Ethylmaleimide (200 microM, 10 min) reduced L-[3H]arginine uptake by 70 % in control cells, but had no effect on PMA-treated (20 or 2 h) cells. 8. In alveolar macrophages, multiple transport systems are involved in L-arginine uptake, which is markedly stimulated by protein kinase C, probably by modulation of the activity of already expressed cationic amino acid transporters.
Institute of Pharmacology and Toxicology, University of Bonn, Reuterstrasse 2b, D-53113 Bonn, Germany. racke.kurt@uni-bonn.de
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Racké
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Hey
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Mössner
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Hammermann
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Wessler
D026923:Amino Acid Transport Systems, Basic; D000818:Animals; D001120:Arginine / Q000493:pharmacokinetics*; D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D002273:Carcinogens / Q000494:pharmacology; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005033:Ethylmaleimide / Q000494:pharmacology; D005260:Female; D007700:Kinetics; D007930:Leucine / Q000494:pharmacology; D016676:Macrophages, Alveolar / Q000737:chemistry / Q000201:enzymology*; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008815:Mice, Inbred Strains; D011493:Protein Kinase C / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D011817:Rabbits; D051381:Rats; D017207:Rats, Sprague-Dawley; D012964:Sodium / Q000494:pharmacology; D013045:Species Specificity; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014316:Tritium
D026923:Amino Acid Transport Systems, Basic; D002273:Carcinogens; D002352:Carrier Proteins; D004791:Enzyme Inhibitors; D008565:Membrane Proteins; D012333:RNA, Messenger; D014316:Tritium; D001120:Arginine; D012964:Sodium; D011493:Protein Kinase C; D007930:Leucine; D013755:Tetradecanoylphorbol Acetate; D005033:Ethylmaleimide