Regulation of L-arginine uptake by Ca(2+) in human platelets.
L-Arginine uptake and Ca(2+) changes in unstirred platelets activated by thrombin, collagen and Ca(2+) ionophore A23187 were evaluated. Thrombin did not affect L-arginine uptake at short incubation times (2-15 min), but at prolonged times slowed down the amino acid transport. Collagen was ineffective. A23187 decreased the L-arginine uptake in a dose-dependent manner, producing the maximal inhibition at 5 microM. In FURA 2-loaded platelets collagen did not modify Ca(2+) basal level, thrombin induced a late Ca(2+) rise and A23187 dose-dependently increased cytosolic Ca(2+), eliciting the highest increase at 5 microM. It is likely that L-arginine uptake is inversely modulated by Ca(2+) concentrations and is inhibited during platelet stimulation with agonists which induce cytosolic Ca(2+) elevation.
Giovine
M
M
Dipartimento di Medicina Sperimentale, sezione Biochimica, Università di Genova, Viale Benedetto XV 1, 16132, Genova, Italy.
Signorello
M G
MG
Pozzolini
M
M
Leoncini
G
G
D001120:Arginine / Q000493:pharmacokinetics*; D001792:Blood Platelets / Q000378:metabolism*; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D003094:Collagen / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006490:Hemostatics / Q000494:pharmacology; D006801:Humans; D007476:Ionophores / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D015539:Platelet Activation / Q000187:drug effects; D015398:Signal Transduction; D013917:Thrombin / Q000494:pharmacology; D013997:Time Factors
D006490:Hemostatics; D007476:Ionophores; D009569:Nitric Oxide; D000001:Calcimycin; D003094:Collagen; D001120:Arginine; D013917:Thrombin; D002118:Calcium