Troubleshooting the rabbit ferric chloride-induced arterial model of thrombosis to assess in vivo efficacy of antithrombotic drugs.

INTRODUCTION: The FeCl3-induced arterial model of thrombosis is one of the most widely used animal models to assess arterial efficacy of new antithrombotic drug candidates. This model is well-established in rodents but in a less extent in the rabbit. In this work, we present a methodology for a rabbit FeCl3-induced arterial model of thrombosis derived from our troubleshooting which allows the generation of reliable efficacy data for new antithrombotic drug candidates. METHODS: Rabbits were administered with heparin 4.5U/kg/min, argatroban 10µg/kg/min or saline by intravenous infusion. The blood flow was monitored using a Doppler flow probe. The time from the application of FeCl3 to the recorded zero blood flow was defined as the time to occlusion, with a maximum recording time of 60min post-FeCl3 application. After 30min of infusion, thrombosis was induced by wrapping a FeCl3-saturated filter paper around the carotid artery caudal to the flow probe. Animals were subject to exclusion criteria based on the visual aspect of the artery FeCl3-induced injury and based on changes in blood flow upon FeCl3 application. RESULTS: Following the application of FeCl3, a mean time to occlusion for saline, heparin and argatroban of 24.3±1.8, 52.5±4.8 and 53.5±4.5min was obtained, respectively. Mean time to occlusion for heparin and argatroban administered groups was significantly different when compared to the saline-treated group (p<0.05). These results for the test compounds represent approximately 80% of the maximum possible prolongation. DISCUSSION: The rabbit FeCl3-induced arterial model of thrombosis presented in this paper derived from our troubleshooting is sensitive and reproducible for the generation of accurate and reliable efficacy data in the assessment of new antithrombotic agents in preclinical drug development.

[Study of dahuangzhechong pills on anti-arterial thrombosis with the orthogonal design].

OBJECTIVE: To screen the main component of Dahuangzhechong pill's anti-arterial thrombosis with the orthogonal design and refine Dahuangzhechong pills. METHODS: In accordance with the orthogonal design table (L(16)2(15)), divided herbs into 16 groups and made the appropriate liquid. The liquid was gave to SD rats by intragastric administration,the model group, normal control group received the same volume of physiological saline. Isolated rats' carotid artery after intragastric administration a week,modeled according to ferric chloride inducement the carotid artery thrombosis method, then collected blood, detected content of platelet, thromboxane B2 (TXB2) and 6-keto-prostaglandin F1alpha (6-keto-PGF1alpha), sheared and measured dry weight of the modeling artery, then placed arteries in 10% formalin fixation, observed morphological changes in vascular tissue by HE staining. RESULTS: Pathological examination revealed: each experimental group had thrombosis, softening, dissolution, absorption, and intimal injury, but the severity of thrombosis were diferent. Orthogonal analysis showed: 1, influence on dry weight of thrombus: rhubarb, ground beetle, leeches, peach seed, dry paint, except dry paint P<0.05, the others P<0.01.2, influence on plasma 6- keto-PGF1alpha level: peach seed, dry paint, ground beetle, gadfly, grubs, leeches, rhubarb, except rhubarb P<0.05, the others P<0.01.3, influence on plasma TXB2: ground beetle, peach seed, dried paint, rhubarb, leeches, except leech P<0.05, the others P<0.01.4, influence on platelet count: peach seed, dry paint, rhubarb, ground beetle, gadfly, leeches, except gadfly, leeches P<0.05, the others P<0.01. CONCLUSION: Anti-artery thrombosis of Dahuangzhechong Pill is most closely related with rhubarb, ground beetle, leeches, peach seed, dry paint and gadfly.

Effect of Chinese herbal medicine for activating blood circulation and detoxifying on expression of inflammatory reaction and tissue damage related factors in experimental carotid artery thrombosis rats.

OBJECTIVE: To observe the pharmaceutical effect of Chinese drugs for activating blood circulation (Xiongshao Capsule, XSC, ) and for activating blood circulation and detoxification (Xiongshao Capsule and Huanglian Capsule, XSHLC, ) in terms of the indices of thrombosis, inflammatory reaction and tissue damage related factors in experimental carotid artery thrombosis rats. METHODS: Fifty Wistar rats were randomly divided into the sham operation group, the model group, the Simvastatin group (SG), the activating blood circulation (ABC) group, and the activating blood circulation and detoxifying (ABCD) group, with 10 rats in each group. Simvastatin (1.8 mg/kg), XSC (0.135 g/kg) and XSHLC (0.135 g/kg) were administered to Simvastatin, ABC and ABCD group by gastrogavage, and an equal volume of normal saline was given to the sham operation group and the model group. After 2 weeks of successive medication, the rats in the model and all drug therapy groups were made into experimental carotid artery thrombosis model. The serum levels of matrix metalloproteinases (MMP-9), tissue inhibitors to metalloproteinase (TIMP-1), granule membrane protein-140 (GMP-140), tissue-type plasminogen activator (t-PA), high-sensitivity C-reactive protein (hs-CRP) and interleukin-6 (IL-6) were detected with enzyme-linked immunoassay 24 h later. RESULTS: Compared with the model group, the levels of serum GMP-140, hs-CRP, IL-6 and MMP-9 were significantly decreased, and the level of t-PA was significantly increased in the ABC and ABCD group ( P<0.05), while the level of serum hs-CRP in ABCD group decreased significantly compared with that in the ABC group (P<0.05). CONCLUSIONS: Chinese drugs both for activating blood circulation and for activating blood circulation and detoxifying have good effects on regulating indices of thrombosis, inflammatory reaction and tissue damage in experimental carotid artery thrombosis rats. The effect of activating blood circulation and detoxifying drugs on regulating the level of serum hs-CRP is superior to that of activating blood circulation drug alone.

Honokiol inhibits arterial thrombosis through endothelial cell protection and stimulation of prostacyclin.

AIM: To study the effect of honokiol on arterial thrombosis and endothelial cells. METHODS: Rabbit platelet aggregation was performed with Borns turbid method. Thrombosis was produced by the endothelial injury stimulated with electric current. Rat aortic endothelial cells (RAEC) were cultured and cell viability was assessed using the MTT assay. Nitric oxide (NO) concentrations in serum-free media of RAEC were determined using the kinetic cadmium-reduction method. The stable metabolite prostacyclin was measured in serum-free media of RAEC by radioimmunoassay. RESULTS: Honokiol (37.6-376 micromol/L) decreased rabbit platelet aggregation in vitro in a concentration-dependent manner, while intravenously injection of honokiol (0.12-12 microg/kg) significantly inhibited rabbit platelet aggregation induced by collagen ex vivo. In the electrical current-stimulated carotid thrombosis model in rats, honokiol (5-50 microg/kg, iv) prolonged the thrombus occlusion time in a does-dependent manner. In vitro honokiol (0.376-37.6 micromol/L) effectively protected cultured RAEC against oxidized low density lipoprotein (ox-LDL) injury, and significantly increased 6-keto-PGF1alpha (the stable metabolite of prostacyclin) in serum-free media of RAEC. Honokiol also increased NO level in RAEC serum-free medium at a lower concentration range (0.0376-0.376 micromol/L), but honokiol 3.76 micromol/L decreased NO level. CONCLUSION: Honokiol is a potent arterial thrombosis inhibitor. Endothelial cell protection and the stimulation of prostacyclin release may be its main anti-thrombosis mechanism. Stimulation of NO release in endothelial cells may play a role, but it is not a key factor.

Ethanol plus caffeine (caffeinol) for treatment of ischemic stroke: preclinical experience.

BACKGROUND AND PURPOSE: Ethanol and caffeine are 2 common psychoactive dietary components. We have recently shown that low-dose ethanol plus caffeine results in a 70% to 80% reduction of infarct volume after reversible common carotid/middle cerebral artery (CCA/MCA) occlusion in rats. The combination (caffeinol) was effective after either oral pretreatment or intravenous administration starting up to 2 hours after stroke onset. Ethanol alone aggravated ischemic damage, while caffeine alone was without effect. Daily caffeinol for 2 weeks before ischemia eliminated the neuroprotection seen with acute treatment (tolerance). The purpose of our present study was to further characterize the properties of caffeinol as a possible treatment for ischemic stroke. METHODS: The transient CCA/MCA occlusion model was used in all experiments. Five sets of experiments were conducted (1) to test the effectiveness of various doses of ethanol (0.2 to 0.65 g/kg) and caffeine (3 to 10 mg/kg) in the caffeinol mixture; (2) to test whether the neuroprotective dose of caffeinol can improve behavioral dysfunction; (3) to test whether chronic ethanol or caffeine before ischemia will affect efficacy of caffeinol treatment; (4) to test whether the protective effect of caffeinol can be improved by pairing it with 35 degrees C hypothermia; and (5) to test whether caffeinol affects frequency of hemorrhage after administration of recombinant tissue plasminogen activator (rtPA) in ischemic animals. RESULTS: Doses as low as 0.2 g/kg of ethanol and 6 mg/kg of caffeine in the caffeinol were effective in reducing cortical infarct volume and behavioral dysfunction after transient CCA/MCA occlusion. Daily exposure to ethanol but not caffeine before CCA/MCA occlusion eliminated the therapeutic efficacy of acute caffeinol treatment, similar to the tolerance observed after chronic exposure to caffeinol. The therapeutic effect of caffeinol could be further improved by pairing it with mild intraischemic hypothermia, and caffeinol did not increase hemorrhagic infarction when given in combination with rtPA. CONCLUSIONS: Low doses of caffeinol, equivalent to no more than 2 to 3 cups of strong coffee and 1 cocktail, are consistently and highly neuroprotective, are well tolerated, can be added to other therapies to increase the effect of each, and do not interfere with or complicate rtPA therapy. Caffeinol is an appropriate candidate for clinical trial in stroke patients, although it may be less effective in patients with regular alcohol intake.

Effect of a synthetic factor Xa inhibitor, YM-60828, on blood vessel patency in combination with a thrombolytic agent and on blood loss from the operation site in a rat model of arterial thrombosis.

We examined the adjunctive effect of a novel factor Xa inhibitor, YM-60828, on vessel patency and blood loss from the operation site after successful thrombolysis with a modified tissue-type plasminogen activator (moPA) in an electrically-induced carotid artery thrombosis model in rats. Five minutes after the induction of occlusive thrombus, a test drug (YM-60828, argatroban, heparin or saline) was administered by i.v. bolus injection followed by continuous infusion. Thrombolysis was induced with moPA by i.v. bolus injection at a dose of 650,000 IU/ kg. YM-60828 at 1 mg/kg i.v. followed by 3 mg/kg/h significantly prevented reocclusion, increased the duration of patency, and improved vessel patency after successful thrombolysis without any significant increase in blood loss from the operation site. Argatroban at 1 mg/kg i.v. followed by 3 mg/kg/h and heparin at 300 U/kg i.v. followed by 150 U/kg/h also significantly improved these parameters, but were accompanied by a significant increase in blood loss. These results suggest that the factor Xa inhibitor YM-60828 may be a potent and useful adjunctive agent with a lower risk of bleeding complications than argatroban and heparin in thrombolytic therapy.

Combined use of aspirin and heparin inhibits in vivo acute carotid thrombosis.

BACKGROUND AND PURPOSE: Carotid atherosclerotic thrombosis is an important cause of ischemic stroke in Western countries. The therapeutic efficacy of either aspirin or heparin alone in this setting is still controversial. Recently we developed a simple model, the "clamp" method, to induce acute carotid mural thrombosis in vivo in guinea pigs. In this study, we used this model to evaluate the antithrombotic effects of aspirin, heparin, and their combination. METHODS: Sixty-four male guinea pigs were divided equally into control, aspirin, heparin, and combined groups. Physiological saline, aspirin (5 mg/kg body wt), heparin (200 units/kg body wt), or a combination of aspirin and heparin, respectively, was injected via the jugular vein before the use of the clamp method. Thirty minutes after the injection of saline or drug(s), Péan's forceps was used to clamp the carotid artery at a tangent angle for 3 minutes. One hour later, the carotid artery was resected and prepared for observation under a scanning electron microscope or light microscope to evaluate the degree of mural thrombosis. RESULTS: The results showed that the combination of aspirin and heparin had an excellent effect in inhibiting in vivo acute carotid thrombosis (p < 0.001) and was significantly better than the effect of aspirin alone (p < 0.01) or heparin alone (p < 0.01). CONCLUSIONS: Our study clearly demonstrated that the combined use of aspirin and heparin produced a much better antithrombotic effect than either agent alone at sites of carotid endothelial injury when given before the injury. This combined regimen may be useful clinically in acute carotid thrombosis secondary to carotid diseases or carotid endarterectomy.