title: YC-1 inhibited human platelet aggregation through NO-independent activation of soluble guanylate cyclase.
abstract: 1. Our previous study demonstrated that YC-1, a derivative of benzylindazole, is a novel activator of soluble guanylate cyclase (sGC) in rabbit platelets. This work investigated whether the antiplatelet effect of YC-1 was mediated by a nitric oxide (NO)/sGC/cyclic GMP pathway in human platelets. 2. In human washed platelets, YC-1 inhibited platelet aggregation and ATP released induced by U46619 (2 microM), collagen (10 micro ml(-1)) and thrombin (0.1 u ml(-1)) in a concentration-dependent manner with IC50 values of (microM) 2.1 +/- 0.03, 11.7 +/- 2.1 and 59.3 +/- 7.1, respectively. 3. In a 30,000 g supernatant fraction from human platelet homogenate, YC-1 (5-100 microM) increased sGC activity in a concentration-dependent manner. At the same concentration-range, YC-1 elevated cyclic GMP levels markedly, but only slightly elevated cyclic AMP levels in the intact platelets. 4. MY-5445, a selective inhibitor of cyclic GMP phosphodiesterase, potentiated the increases in cyclic GMP caused by YC-1, and shifted the concentration-anti-aggregation curve of YC-1 to the left. In contrast, HL-725, a selective inhibitor of cyclic AMP phosphodiesterase, did not affect either the increases in cyclic nucleotides or the anti-aggregatory effect caused by YC-1. 5. Methylene blue, an inhibitor of sGC, blocked the increases of cyclic GMP caused by YC-1, and attenuated markedly the anti-aggregatory effect of YC-1. The adenylate cyclase inhibitor, 2',5'-dideoxyadenosine (DDA) did not affect YC-1-induced inhibition of platelet aggregation. 6. Haemoglobin, which binds NO, prevented the activation of sGC and anti-aggregatory effect caused by sodium nitroprusside, but did not affect YC-1 response. 7. These results would suggest that YC-1 activates sGC of human platelets by a NO-dependent mechanism, and exerts its antiplatelet effects through the sGC/cyclic GMP pathway.
authors.affiliation: Pharmacological Institute, College of Medicine, National Taiwan University, Taipei.
authors.forename: C C
authors.initials: CC
authors.lastname: Wu
authors.forename: F N
authors.initials: FN
authors.lastname: Ko
authors.forename: S C
authors.initials: SC
authors.lastname: Kuo
authors.forename: F Y
authors.initials: FY
authors.lastname: Lee
authors.forename: C M
authors.initials: CM
authors.lastname: Teng
mesh_terms: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000255:Adenosine Triphosphate / Q000494:pharmacology; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism*; D003094:Collagen / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism; D016048:Dideoxyadenosine / Q000031:analogs & derivatives / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D005663:Furans / Q000494:pharmacology*; D006162:Guanylate Cyclase / Q000378:metabolism*; D006454:Hemoglobins / Q000502:physiology; D006801:Humans; D007191:Indazoles / Q000494:pharmacology*; D009569:Nitric Oxide / Q000378:metabolism*; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010793:Phthalazines / Q000494:pharmacology; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D011450:Prostaglandin Endoperoxides, Synthetic / Q000494:pharmacology; D012995:Solubility; D013917:Thrombin / Q000494:pharmacology; D013928:Thromboxane A2 / Q000031:analogs & derivatives / Q000494:pharmacology; D014662:Vasoconstrictor Agents / Q000494:pharmacology
chemical_list: D005663:Furans; D006454:Hemoglobins; D007191:Indazoles; D010726:Phosphodiesterase Inhibitors; D010793:Phthalazines; D010975:Platelet Aggregation Inhibitors; D011450:Prostaglandin Endoperoxides, Synthetic; D014662:Vasoconstrictor Agents; C090937:3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole; D009569:Nitric Oxide; D016048:Dideoxyadenosine; D013928:Thromboxane A2; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000255:Adenosine Triphosphate; D003094:Collagen; C021008:2',5'-dideoxyadenosine; D000242:Cyclic AMP; D013917:Thrombin; D006162:Guanylate Cyclase; C052490:MY 5445; D006152:Cyclic GMP