title: Antiplatelet effect of AMP-activated protein kinase activator and its potentiation by the phosphodiesterase inhibitor dipyridamole.
abstract: AMP-activated protein kinase (AMPK) activates endothelial nitric oxide synthase (eNOS) via phosphorylation at the activating site. The eNOS-nitric oxide (NO)/soluble guanylate cyclase (sGC)-cGMP/cGMP-dependent protein kinase (PKG) signaling axis is a major antiaggregatory mechanism residing in platelets. Based on the hypothesis that direct activation of AMPK might be a potential strategy to inhibit platelet aggregation, the antiplatelet effect of AMPK activators was investigated. Treatment of isolated platelets with the AMPK activator, 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR) resulted in AMPK activation and a decrease in aggregation, which was abolished by pretreatment with the AMPK inhibitors compound C (CC) and ara-A. Such an AMPK-dependent antiaggregatory effect was also observed with other AMPK activators such as A-769662 and PT1. AICAR induced eNOS activation was followed by NO synthesis, cGMP production, and subsequent phosphorylation of vasodilator-stimulated phosphoprotein (VASP), a PKG substrate. All these events were blocked by CC or ara-A pretreatment, and each event was inhibited by the eNOS inhibitor L-NAME, the sGC inhibitor ODQ, and the PKG inhibitor Rp-8-pCPT-cGMPS. Simultaneous treatment of dipyridamole, a phosphodiesterase (PDE) inhibitor, with AICAR potentiated the antiaggregatory effect by enhancing the cGMP elevation. Administration of AICAR increased platelet cGMP and prolonged FeCl3-induced arterial occlusion time in rats, which further increased in combination with dipyridamole. In conclusion, AMPK activators inhibited platelet aggregation by stimulating the eNOS-NO/sGC-cGMP/PKG signaling pathway. The antiplatelet effect of AMPK activators could be potentiated in combination with a PDE inhibitor through the common mechanism of elevating cGMP. Thus, AMPK may serve as a potential target for antiplatelet therapy.
authors.affiliation: College of Pharmacy, Dongguk University, Gyeonggi-do, Goyang 410-820, Republic of Korea.
authors.forename: Yingqiu
authors.initials: Y
authors.lastname: Liu
authors.forename: Seok-Jeong
authors.initials: SJ
authors.lastname: Oh
authors.forename: Kyung-Hwa
authors.initials: KH
authors.lastname: Chang
authors.forename: Yoon-Gyoon
authors.initials: YG
authors.lastname: Kim
authors.forename: Moo-Yeol
authors.initials: MY
authors.lastname: Lee
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives* / Q000097:blood / Q000494:pharmacology; D000818:Animals; D006152:Cyclic GMP / Q000378:metabolism; D004176:Dipyridamole / Q000494:pharmacology*; D004195:Disease Models, Animal; D004789:Enzyme Activation / Q000187:drug effects; D020536:Enzyme Activators / Q000494:pharmacology*; D008297:Male; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012265:Ribonucleotides / Q000097:blood / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D013927:Thrombosis / Q000188:drug therapy / Q000378:metabolism
chemical_list: D020536:Enzyme Activators; D010726:Phosphodiesterase Inhibitors; D010975:Platelet Aggregation Inhibitors; D012265:Ribonucleotides; D000620:Aminoimidazole Carboxamide; D004176:Dipyridamole; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; D055372:AMP-Activated Protein Kinases; C031143:AICA ribonucleotide; D006152:Cyclic GMP
keywords: AMP-activated protein kinase (AMPK); Antiplatelet therapy; Platelet aggregation; Thrombosis 5-Aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR)