Paradoxical effect of l-arginine: Acceleration of endothelial cell senescence

We have recently shown that inhibition of nitric oxide (NO) synthesis by asymmetrical dimethylarginine (ADMA) accelerated endothelial cell (EC) senescence which was prevented by coincubation with L-arginine; however the effect of long-term treatment of l-arginine alone on senescence of ECs have not been investigated. Human ECs were cultured in medium containing different concentrations of L-arginine until senescence. L-Arginine paradoxically accelerated senescence indicated by inhibiting telomerase activity. Moreover, L-arginine decreased NO metabolites, increased peroxynitrite, and 8-iso-prostaglandin F(2alpha) formation. In old cells, the mRNA expression of human amino acid transporter (h…