The anti-platelet agent, ticlopidine, upregulates interleukin-1-Beta-stimulated nitric oxide production in cultured rat vascular smooth muscle cells.
BACKGROUND
Hemodialysis patients who had been treated with anti-platelet aggregation drugs, including ticlopidine, sometimes developed hypotension. The mechanism by which ticlopidine lowers the blood pressure in hemodialysis patients is unclear. To elucidate the mechanism of the action of this drug, we investigated cytokine-stimulated nitric oxide (NO) metabolism by ticlopidine in cultured rat vascular smooth muscle cells (VSMC).


METHODS
Nitrite, a stable metabolite of NO, and intracellular cAMP and cGMP contents were assayed by the Griess method and enzyme immunoassay, respectively. iNOS mRNA and protein expressions were analyzed by Northern blotting and Western blotting.


RESULTS
Ticlopidine enhanced interleukin-1beta (IL-1beta)-induced nitrite production in a dose- and time-dependent manner. The mRNA and protein expressions of inducible NO synthase were upregulated by ticlopidine in a dose- and time-dependent manner. IL-1beta alone stimulated both intracellular cAMP and cGMP contents, and the addition of ticlopidine further enhanced their contents. KT 5720, a selective inhibitor of protein kinase A, but not KT 5823, a selective inhibitor of protein kinase G, abolished the enhancement of IL-1beta-induced nitrite production by ticlopidine. In addition, a phosphodiesterase inhibitor, isobutylmethylxanthine, enhanced IL-1beta and ticlopidine induced nitrite production.


CONCLUSIONS
We concluded that ticlopidine enhanced the IL-1beta-induced NO production via cAMP and subsequent activation of protein kinase A in cultured rat VSMC.
Inoue
Makoto
M
Division of Nephrology, Department of Medicine, Jichi Medical School, Tochigi, Japan.
Kusano
Eiji
E
Ito
Chiharu
C
Akimoto
Tetsu
T
Iimura
Osamu
O
Nemoto
Jun
J
Amemiya
Morimasa
M
Muto
Shigeaki
S
Asano
Yasushi
Y
D000818:Animals; D001011:Aorta / Q000166:cytology; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism; D007375:Interleukin-1 / Q000494:pharmacology*; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D009566:Nitrates / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000235:genetics; D052247:Nitric Oxide Synthase Type II; D009573:Nitrites / Q000378:metabolism; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D013988:Ticlopidine / Q000494:pharmacology*; D015854:Up-Regulation / Q000187:drug effects
D007375:Interleukin-1; D009566:Nitrates; D009573:Nitrites; D010726:Phosphodiesterase Inhibitors; D010975:Platelet Aggregation Inhibitors; D012333:RNA, Messenger; D009569:Nitric Oxide; D000242:Cyclic AMP; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D006152:Cyclic GMP; D013988:Ticlopidine