Probucol decreases asymmetrical dimethylarginine level by alternation of protein arginine methyltransferase I and dimethylarginine dimethylaminohydrolase activity.
OBJECTIVE
Asymmetric dimethylarginine (ADMA), an endogenous nitric oxide synthase inhibitor (NOS), may play an important role in endothelium dysfunction. Probucol, a potent antioxidant drug, may improve endothelium function via reduction of NOS inhibitor level. The present study examined whether the decreased level of ADMA by probucol is related to enhancement of protein arginine methyltransferase I (PRMT I) expression and reduction of dimethylarginine dimethylaminohydrolase (DDAH) activity.


METHODS
Endothelial cells were cultured and used for all these studies. ADMA concentration and DDAH activity were determined by HPLC. Expression of PRMT I and eNOS were characterized by western blot.


RESULTS
Pretreatment with oxidized-low density lipoprotein (ox-LDL) (10, 30 or 100 microg/ml) or lysophosphatidylcholine (LPC) (1.0, 2.5 or 5.0 microg/ml) for 12, 24 or 48 h markedly increased the activity of lactate dehydrogenase (LDH) in cultured endothelial cell. Incubation ofendothelial cells with ox-LDL (100 microg/ml) or LPC (5.0 microg/ml) for 48 h significantly increased the expression of PRMT I, and levels of MDA and ADMA, and decreased the concentration of nitrite/nitrate, the expression of eNOS and the activity of DDAH. Probucol significantly decreased the level of ADMA, concomitantly with reduction of PRMT I expression and elevation of DDAH activity and up-regulation of eNOS expression.


CONCLUSIONS
In summary, the present results suggest that the protective effect of probucol on endothelium is related to reduction of ADMA concentration by inhibition of PRMT I expression and enhancement of DDAH activity.
Jiang
Jun-Lin
JL
Department of Pharmacology, School of Pharmaceutical Sciences, Central South University, Xiang-Ya Road #110, Changsha, Hunan, 410078, PR China.
Zhang
Xiao-Hong
XH
Li
Nian-Sheng
NS
Rang
Wei-Qing
WQ
Feng-Ye
Hu
Chang-Ping
CP
Li
Yuan-Jian
YJ
Deng
Han-Wu
HW
D000581:Amidohydrolases / Q000378:metabolism*; D000975:Antioxidants / Q000494:pharmacology*; D001120:Arginine / Q000031:analogs & derivatives* / Q000378:metabolism; D002460:Cell Line; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008077:Lipoproteins, LDL / Q000494:pharmacology; D008315:Malondialdehyde / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D011341:Probucol / Q000494:pharmacology*; D011484:Protein-Arginine N-Methyltransferases / Q000378:metabolism*
D000975:Antioxidants; D008077:Lipoproteins, LDL; C099252:oxidized low density lipoprotein; D009569:Nitric Oxide; D008315:Malondialdehyde; C018524:N,N-dimethylarginine; D001120:Arginine; D007770:L-Lactate Dehydrogenase; D052250:Nitric Oxide Synthase Type III; D011484:Protein-Arginine N-Methyltransferases; D000581:Amidohydrolases; C059999:dimethylargininase; D011341:Probucol