title: Inhibitory effects of sodium quercetin monosulfate on pig platelet aggregation induced by thrombin.
abstract: OBJECTIVE
  To study the inhibitory effects of sodium quercetin monosulfate (SQMS) on pig platelet aggregation induced by thrombin.
  
  
  METHODS
  Platelet aggregation was analyzed by turbidimetry. Cytosolic free calcium concentration ([Ca2+]i) was determined by Fura-2 fluorescence. Activity of protein kinase C (PKC) was assayed by incubating PKC with histone III S and [gamma-32 P] ATP. The cytoskeletal proteins were precipitated by Triton X-100 and separated by SDS-PAGE.
  
  
  RESULTS
  SQMS inhibited the platelet aggregation induced by thrombin 500 U.L-1 with IC50 132 (50-347) mumol.L-1. SQMS inhibited Ca2+ influx in blood platelets induced by thrombin 500 U.L-1 in the presence of extracellular Ca2+ 1 mmol.L-1 with IC50 20 (9-46) mumol.L-1; SQMS inhibited the internal Ca2+ release in the absence of extracellular Ca2+. SQMS also decreased [Ca2+]i level in quiescent blood platelets. SQMS (10-160 mumol.L-1) inhibited the activity of cytosolic PKC from blood platelets in a concentration-dependent manner, but had no effect on membrane PKC. SQMS (20-80 mumol.L-1) inhibited the actin polymerization induced by thrombin 500 U.L-1 inblood platelets in a concentration-dependent manner.
  
  
  CONCLUSIONS
  SQMS inhibited pig platelet aggregation induced by thrombin and its mechanism might be due to its inhibitions of Ca2+ influx, internal Ca2- release, PKC activity, and actin polymerization.
authors.affiliation: Institute of Medical Biochemistry, Guangdong Medical College, Zhanjiang, China.
authors.forename: W
authors.initials: W
authors.lastname: Liu
authors.forename: Z J
authors.initials: ZJ
authors.lastname: Song
authors.forename: N C
authors.initials: NC
authors.lastname: Liang
authors.forename: J
authors.initials: J
authors.lastname: She
authors.forename: L E
authors.initials: LE
authors.lastname: Mo
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000097:blood*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D011493:Protein Kinase C / Q000097:blood; D011794:Quercetin / Q000031:analogs & derivatives / Q000494:pharmacology*; D013552:Swine; D013917:Thrombin / Q000494:pharmacology
chemical_list: D000199:Actins; D010975:Platelet Aggregation Inhibitors; D011794:Quercetin; D011493:Protein Kinase C; D013917:Thrombin; D002118:Calcium