OBJECTIVE: To investigate the antithrombotic effects of recombinant hirudin and its mechanism. METHODS: Sixty male Kunming mice were randomly divided into 6 group (=10):control group, model group, aspirin (25 mg/kg) group, recombinant hirudinlow, middle and high dose (0.05, 0.1, 0.2 mg/kg) groups.Except mice in control group, 2.5 mg/kg carrageenan was injected intraperitoneallyto mice in the other groups to produce thrombosis on the mice tail. The mice in aspirin group were administrated intraperitoneally 25 mg/kg aspirin, the mice in recombinant hirudinlow, middle and high dose groups were administrated intraperitoneally 0.05, 0.1, 0.2 mg/kg combinanthirudin, the mice in control group and model group were administrated intraperitoneallynormal saline at the same volume respectively at 24 h, 0.5 h before injecting carrageenan and 24 h after injecting carrageenan. The black tail length of mice and the incidence of black tail were observed at 48h after injection of carrageenan; prothrombin time (PT), activated partial thromboplastin time (APTT), tissue plasminogen activator (t-PA), type-1 plasminogen activator inhibitor (PAI-1), 6-keto-PGF1α, and thromboxane B2 (TXB2) level in mice plasma were determined. RESULTS: As compared with control group, the mice in model group presented tail thrombosis; PT level in plasma was significantly shortened (<0.01), PAI-1 and TXB2levels in plasma were significantly increased (<0.01), while the t-PA and 6-keto-PGF1α levels in plasma in model group were significantly decreased (<0.01). As compared with model group, the thrombus length in the tail was significantly shortened (<0.05, <0.01), PT level was obviously prolonged (<0.01), and the plasma levels of PAI-1 and TXB2 were significantly decreased (<0.01), while the plasma levels of t-PA and 6-keto-PGF1α were significantly increased (<0.01)in the mice of recombinant hirudin low dose, middle dose, high dose groups and aspirin group. As compared with aspirin group, the thrombus length in the tail was significantly increased (<0.05), PT level was obviously shortened (<0.01), and the plasma levels of PAI-1 and TXB2 were significantly increased (<0.01)in the mice of recombinant hirudin low dose group; the plasma level of 6-keto-PGF1α was significantly decreased (<0.01, <0.05) in the mice of recombinant hirudin low dose and middle dose groups; the plasma levels of PAI-1 and TXB2 were significantly increased (<0.01, <0.05)in the mice of recombinant hirudin middle dose group. CONCLUSIONS The recombinant hirudin can fight against thrombosis, its antithrombotic mechanisms may be related to its influence on the exogenous coagulation system and the promotion of fibrinolysis function.
Animals ; Blood Coagulation ; Fibrinolytic Agents ; Hirudins ; pharmacology ; Male ; Mice ; Recombinant Proteins ; Thromboxane B2 ; Tissue Plasminogen Activator

Tomato extract has been shown to exert antiplatelet activity in vitro and to change platelet function ex vivo, but with limitations. In this study, antiplatelet activity of water soluble tomato concentrate (Fruitflow I) and dry water soluble tomato concentrate (Fruitflow II) was investigated using rat platelets. Aggregation was induced by collagen and adenosine diphosphate and granule-secretion, [Ca2+]i, thromboxane B2, cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) levels were examined. The activation of integrin αIIbβ3 and phosphorylation of signaling molecules, including mitogen-activated protein kinase (MAPK) and PI3K/Akt, were investigated by flow cytometry and immunoblotting, respectively. Prothrombin time (PT) and activated partial thromboplastin time (aPTT) were examined. Moreover, in vivo thrombus weight was tested by an arteriovenous shunt model. Fruitflow I and Fruitflow II significantly inhibited agonist induced platelet aggregation, adenosine triphosphate and serotonin release, [Ca2+]i, and thromboxane B2 concentration, while having no effect on cAMP and cGMP levels. Integrin αIIbβ3 activation was also significantly decreased. Moreover, both concentrates reduced phosphorylation of MAPK pathway factors such as ERK, JNK, P38, and PI3K/Akt. In vivo thrombus formation was also inhibited. Taken together, these concentrates have the potential for ethnomedicinal applications to prevent cardiovascular ailments and can be used as functional foods.
Adenosine Diphosphate ; Adenosine Monophosphate ; Adenosine Triphosphate ; Animals ; Blood Platelets* ; Cardiovascular Diseases ; Collagen ; Flow Cytometry ; Functional Food ; Guanosine Monophosphate ; Immunoblotting ; In Vitro Techniques ; Lycopersicon esculentum* ; Partial Thromboplastin Time ; Phosphorylation ; Platelet Aggregation ; Protein Kinases* ; Prothrombin Time ; Rats ; Serotonin ; Thrombosis ; Thromboxane B2 ; Water*

This study was designed to investigate inhibitory effects and possible mechanisms of snake venom tripeptide (pENW) on platelet adhesion in order to promote the development of a novel anti-platelet therapy. To study the inhibitory effects of pENW on platelet adhesion, washed platelets pre-incubated with pENW (116.5-466.2 μmol x L(-1)) were used to test the ability of platelet adhesion to fibrinogen. Effect of pENW on fibrin clot retraction was also tested. Effect of pENW on platelets viability was tested by MTT assay. Effect of pENW on reactive-oxygen species (ROS) levels of platelet was studied by flow cytometry assay. Calcium mobilization in Fura-2/AM-loaded platelets was monitored with a spectrofluorimeter. Cyclic guanosine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP), thromboxane A2 (determined as its metabolite thromboxane B2) were measured using enzyme immunoassay kits. Akt, ERK and p38 phosphorylation were tested by Western blot. The results showed that pENW inhibited platelet adhesion and fibrin clot retraction in a concentration-dependent manner without cytotoxicity. Intracellular cGMP and cAMP in both resting and thrombin-activated platelets were increased by pENW. In addition, pENW attenuated intracellular Ca2+ mobilization and TXA2 production in platelets stimulated by thrombin. As shown by Western blot assay, Akt, ERK and p38 phosphorylation in thrombin-induced platelet were attenuated by pENW. However, inhibitory effects of pENW had nothing to do with ROS. Thus, pENW exhibited a significant inhibition on platelet adhesion to fibrinogen, which means pENW could block the first step of thrombosis as while as retard the more stable clot formation. The mechanisms of pENW on inhibition platelet adhesion might be related to instant regulations, such as protein kinases.
Blood Platelets ; drug effects ; Blotting, Western ; Calcium ; metabolism ; Cyclic AMP ; metabolism ; Cyclic GMP ; metabolism ; Flow Cytometry ; Phosphorylation ; Platelet Aggregation ; drug effects ; Reactive Oxygen Species ; metabolism ; Snake Venoms ; chemistry ; Thromboxane A2 ; metabolism ; Thromboxane B2 ; metabolism

BACKGROUNDAngiotensin type 1 receptor (AT 1 R) antagonists are extensively used for blood pressure control in elderly patients with hypertension. This study aimed to investigate the inhibitory effects of AT 1 R antagonist valsartan on platelet aggregation and the occurrence of cardio-cerebral thrombotic events in elderly patients with hypertension.

METHODSTwo-hundred and ten patients with hypertension and aged > 60 years were randomized to valsartan (n = 140) or amlodipine (n = 70) on admission. The primary endpoint was platelet aggregation rate (PAR) induced by arachidonic acid at discharge, and the secondary endpoint was the rate of thrombotic events including brain infarction and myocardial infarction during follow-up. Human aortic endothelial cells (HAECs) were stimulated by angiotensin II (Ang II, 100 nmol/L) with or without pretreatment of valsartan (100 nmol/L), and relative expression of cyclooxygenase-2 (COX-2) and thromboxane B 2 (TXB 2 ) and both p38 mitogen-activated protein kinase (p38MAPK) and nuclear factor-kB (NF-kB) activities were assessed. Statistical analyses were performed by GraphPad Prism 5.0 software (GraphPad Software, Inc., California, USA).

RESULTSPAR was lower after treatment with valsartan (11.49 ± 0.69% vs. 18.71 ± 2.47%, P < 0.001), associated with more reduced plasma levels of COX-2 (76.94 ± 7.07 U/L vs. 116.4 ± 15.89 U/L, P < 0.001) and TXB 2 (1667 ± 56.50 pg/ml vs. 2207 ± 180.20 pg/ml) (all P < 0.001). Plasma COX-2 and TXB 2 levels correlated significantly with PAR in overall patients (r = 0.109, P < 0.001). During follow-up (median, 18 months), there was a significantly lower thrombotic event rate in patients treated with valsartan (14.3% vs. 32.8%, P = 0.002). Relative expression of COX-2 and secretion of TXB 2 with concordant phosphorylation of p38MAPK and NF-kB were increased in HAECs when stimulated by Ang II (100 nmol/L) but were significantly decreased by valsartan pretreatment (100 nmol/L).

CONCLUSIONSAT 1 R antagonist valsartan decreases platelet activity by attenuating COX-2/TXA 2 expression through p38MAPK and NF-kB pathways and reduces the occurrence of cardio-cerebral thrombotic events in elderly patients with hypertension.

Aged ; Aged, 80 and over ; Angiotensin Receptor Antagonists ; therapeutic use ; Blood Platelets ; drug effects ; Blotting, Western ; Cell Line ; Cyclooxygenase 2 ; blood ; Female ; Humans ; Hypertension ; drug therapy ; Male ; Platelet Aggregation ; drug effects ; Real-Time Polymerase Chain Reaction ; Tetrazoles ; therapeutic use ; Thrombosis ; blood ; drug therapy ; Thromboxane B2 ; blood ; Valine ; analogs & derivatives ; therapeutic use ; Valsartan

OBJECTIVETo observe the effects of Rubiae Radix et Rhizoma (RRR) and carbonized Rubiae Radix et Rhizoma (CRRR) on the acute blood stasis rat model, and reveal their differences in efficacy.

METHODThe acute blood stasis model was induced by subcutaneously injecting adrenaline hydrochloride and soaking in ice water. Yunnan Baiyao was used as the positive control drug, and administered for consecutively seven days. This model was adopted to observe the effect of high, middle and low dose RRR and CRRR groups on hemorheology, thrombin activity, and blood platelet system.

RESULTRRR could significantly reduce the wholeblood viscosity and plasma viscosity of blood stasis rats under different shear rates, and showed certain two-way regulating function in hemostasis. It also showed certain effect on ADP-induced platelet aggregation rate, but which was lower than CRRR. CRRR achieved the main hemostatic mechanism by stimulating intrinsic and extrinsic blood coagulation and fibrinogen, and could significantly enhance the platelet aggregation rate of rats in the acute blood stasis model (P <0. 01).

CONCLUSIONRRR had the effect of removing blood stasis and hemostasis, while CRRR mainly has the hemostatic effect. This further demonstrates the traditional processing theory of "promoting blood circulation with crude herbs and stopping bleeding with processed herbs".

6-Ketoprostaglandin F1 alpha ; blood ; Animals ; Blood Coagulation ; drug effects ; Carbon ; chemistry ; Chemistry, Pharmaceutical ; methods ; Disease Models, Animal ; Drugs, Chinese Herbal ; chemistry ; pharmacology ; Female ; Hemodynamics ; drug effects ; Male ; Medicine, Chinese Traditional ; methods ; Rats ; Rats, Sprague-Dawley ; Rubia ; chemistry ; Thromboxane B2 ; blood

The inhibitory effects of perilla oil on the platelet aggregation in vitro and thrombosis in vivo were investigated in comparison with aspirin, a well-known blood flow enhancer. Rabbit platelet-rich plasma was incubated with perilla oil and aggregation inducers collagen or thrombin, and the platelet aggregation rate was analyzed. Perilla oil significantly inhibited both the collagen- and thrombin-induced platelet aggregations, in which the thromboxane B2 formation from collagen-activated platelets were reduced in a concentration-dependent manner. Rats were administered once daily by gavage with perilla oil for 1 week, carotid arterial thrombosis was induced by applying 35% FeCl3-soaked filter paper for 10 min, and the blood flow was monitored with a laser Doppler probe. Perilla oil delayed the FeCl3-induced arterial occlusion in a dose-dependent manner, doubling the occlusion time at 0.5 mL/kg. In addition, a high dose (2 mL/kg) of perilla oil greatly prevented the occlusion, comparable to the effect of aspirin (30 mg/kg). The results indicate that perilla oil inhibit platelet aggregation by blocking thromboxane formation, and thereby delay thrombosis following oxidative arterial wall injury. Therefore, it is proposed that perilla oil could be a good candidate without adverse effects for the improvement of blood flow.
Animals ; Aspirin ; Blood Platelets* ; Collagen ; Perilla* ; Platelet Aggregation* ; Platelet-Rich Plasma ; Rats ; Thrombin ; Thrombosis* ; Thromboxane B2

OBJECTIVETo investigate the effect of atorvastatin on platelet aggregation and activation in the acute phase following balloon-induced carotid artery injury in rabbits fed cholesterol-enriched diet.

METHODSThirty rabbits were randomly divided into 5 equal groups, namely control group, high-cholesterol group, model group, low-dose (5 mg/kg daily) atorvastatin group, and high-dose (10 mg/kg daily) atorvastatin group. Platelet aggregation rate was measured in the rabbits by turbidimetric platelet aggregometry, and the changes of serum P-selectin and thromboxane B2 (TXB2) levels were detected with enzyme-linked immunosorbent assay (ELISA).

RESULTSCompared with those in the control group, serum P-selectin level increased significantly (P<0.01) but platelet aggregation rate and TXB2 level exhibited no obvious changes in high-cholesterol group. After carotid artery balloon injury, P-selectin and TXB2 levels and platelet aggregation significantly increased in cholesterol-fed rabbits, reaching the peak level at 24 h after the injury (P<0.01). Compared with the model group, low-dose atorvastatin treatment significantly decreased P-selectin and TXB2 levels and inhibited platelet aggregation in cholesterol-fed rabbits following carotid artery balloon injury (P<0.01), and such effects of atorvastatin were more prominent at a higher daily dose of 10 mg/kg (P<0.05).

CONCLUSIONSCarotid artery balloon injury in rabbits fed cholesterol-enriched diet can induce platelet activation and aggregation, which reaches the peak level at 24 h after balloon injury and can be dose-dependently inhibited by atorvastatin in the acute phase following the injury.

Animals ; Atorvastatin Calcium ; Blood Platelets ; Carotid Artery Injuries ; drug therapy ; Cholesterol ; Enzyme-Linked Immunosorbent Assay ; Heptanoic Acids ; pharmacology ; P-Selectin ; metabolism ; Platelet Activation ; Platelet Aggregation ; Pyrroles ; pharmacology ; Rabbits ; Thromboxane B2 ; metabolism

This study is to investigate the effects of paeoniflorin on cerebral blood flow and the balance of PGI2/TXA2 of rats with focal cerebral ischemia-reperfusion injury. A total of 72 SD rats (3) were randomly divided into 6 groups: sham operation group, cerebral ischemia-reperfusion model group (I/R gourp), low (10 mg.kg-1), middle (20 mg.kg-1) and high (40 mg.kg-1) doses of paeoniflorin groups and nimrnodipine group. Focal cerebral ischemia in rats was made by inserting a monofilament suture into internal carotid artery for 90 min and then reperfused for 24 h. The effects of paeoniflorin on neurological deficit scores and the infarction volume of brain were detected. Relative regional cerebral blood flow (rCBF) was continuously monitored over ischemic hemispheres by laser-Doppler flowmetry (LDF). The expression of COX-2 in hippocampal CAl region was estimated by immunohistochemistry and the contents of prostacyclin I2 (PGI2), thromboxane A2 (TXA2), and ratio of PGIJ2/TXA2 in serum were measured by ELISA kits. Paeoniflorin significantly ameliorated neurological scores, reduced the infarction volume, and increased regional cerebral blood flow relative to the I/R group. In addition, paeoniflorin could inhibit COX-2 expression and the release of TXA2 and prevent the downregulation of PGI2 induced by I/R injury. The neuroprotective effects of paeoniflorin against focal cerebral ischemia-reperfusion rats might be attributed to improve the supply of injured hemisphere blood flow and adjust the balance between PGI2/TXA2.
6-Ketoprostaglandin F1 alpha ; blood ; Animals ; Brain ; blood supply ; CA1 Region, Hippocampal ; metabolism ; Cyclooxygenase 2 ; metabolism ; Glucosides ; isolation & purification ; pharmacology ; Infarction, Middle Cerebral Artery ; blood ; metabolism ; pathology ; physiopathology ; Male ; Monoterpenes ; isolation & purification ; pharmacology ; Neuroprotective Agents ; isolation & purification ; pharmacology ; Paeonia ; chemistry ; Plants, Medicinal ; chemistry ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Regional Blood Flow ; drug effects ; Reperfusion Injury ; metabolism ; physiopathology ; Thromboxane B2 ; blood

OBJECTIVETo investigate the effects of Qushuanling Capsule ( QSLC) on thrombus formation and platelet aggregation in rats.

METHODSArteriovenous bypass, venous thrombosis, and middle cerebral artery thrombosis models were used in rats to investigate the anti-thrombotic effects of QSLC, a compound of nine Chinese herbs. The platelet aggregation induced by adenosine diphosphate (ADP), thrombin or arachidonic acid (AA), as well as the contents of thromboxane B(2) (TXB(2)) and 6-keto-prostaglandin F1α (6-keto-PGF1α) in rat plasma and aortic walls, were determined to investigate the possible mechanisms of the anti-thrombotic effects of QSLC.

RESULTSAfter oral administration with QSLC for 7 days, arteriovenous bypass thrombosis was obviously suppressed compared with the model group, venous thrombosis was also obviously suppressed, rat behaviors were obviously improved, and brain infarct size as well as water content were also reduced. The platelet aggregation induced by ADP or thrombin was inhibited by QSLC, but the drug had no effect on AA-induced platelet aggregation and content of TXB(2) and 6-keto-PGF1α in plasma and the aortic wall.

CONCLUSIONThese results suggest that QSLC can be used in the prevention and treatment of thrombotic diseases, and that its mechanism of action may be related to inhibition of platelet aggregation.

6-Ketoprostaglandin F1 alpha ; blood ; Adenosine Diphosphate ; pharmacology ; Animals ; Aorta ; drug effects ; metabolism ; pathology ; Cerebral Infarction ; blood ; drug therapy ; pathology ; Drugs, Chinese Herbal ; pharmacology ; therapeutic use ; Male ; Middle Cerebral Artery ; drug effects ; pathology ; Platelet Aggregation ; drug effects ; Rats ; Rats, Sprague-Dawley ; Thrombosis ; drug therapy ; pathology ; Thromboxane B2 ; blood ; Venous Thrombosis ; drug therapy ; pathology

OBJECTIVETo study the changes of cardiovascular regulating factors in rats during recovery of aerobic exhaustive exercise.

METHODSSixty male Wistar rats were randomly divided into control group, 1 h-exercise group, 3 h-exercise group, exhausted group, 2 h-recovery group and 12 h-recovery group. The rats were killed at corresponding times for each group after an 8-week-long treadmill training, and the levels of NO, ET, ANP and TXB2 in plasma were measured in each group.

RESULTSNO/ET ratio of 1 h-exercise group was significantly higher than that in control group (P < 0.01), while it was significantly decreased in 3 h-exercise group and exhausted group (P < 0.05). ANP contents in rat plasma were significantly higher in 3 h-exercise group, exhausted group and 2 h-recovery group than that in control group (P < 0.05 or P < 0.01). The concentration of TXB2 in plasma was significantly increased in 3 h-exercise group, exhausted group and 2 h-recovery group (P < 0.05).

CONCLUSIONChanges in cardiovascular regulating factors after exhaustive exercise may lead to deficiency of coronary circulation blood/oxygen supply, which may cause exercise-induced fatigue.

Animals ; Atrial Natriuretic Factor ; blood ; Cardiovascular System ; physiopathology ; Endothelins ; blood ; Exercise Test ; Fatigue ; blood ; Male ; Nitric Oxide ; blood ; Physical Conditioning, Animal ; Rats ; Rats, Wistar ; Thromboxane B2 ; blood