A derivative of vitamin B3 applied several days after exposure reduces lethality of severely irradiated mice.

Most, if not all, of the hitherto tested substances exert more or less pronounced pro-survival effects when applied before or immediately after the exposure to high doses of ionizing radiation. In the present study we demonstrate for the first time that 1-methyl nicotinamide (MNA), a derivative of vitamin B3, significantly (1.6 to 1.9 times) prolonged survival of BALB/c mice irradiated at LD30/30 (6.5 Gy), LD50/30 (7.0 Gy) or LD80/30 (7.5 Gy) of γ-rays when the MNA administration started as late as 7 days post irradiation. A slightly less efficient and only after the highest dose (7.5 Gy) of γ-rays was another vitamin B3 derivative, 1-methyl-3-acetylpyridine (1,3-MAP) (1.4-fold prolonged survival). These pro-survival effects did not seem to be mediated by stimulation of haematopoiesis, but might be related to anti-inflammatory and/or anti-thrombotic properties of the vitamin B3 derivatives. Our results show that MNA may represent a prototype of a radioremedial agent capable of mitigating the severity and/or progression of radiation-induced injuries when applied several hours or days after exposure to high doses of ionizing radiation.

Arachidonic Acid-Dependent Pathway Inhibition in Platelets: its Role in Multiple Injury-Induced Coagulopathy and the Potential Mechanisms.

BACKGROUND: Our previous study demonstrated the types of platelet dysfunction varied at early stage (∼3 h) in trauma-induced coagulopathy (TIC) caused by different types of injuries. And arachidonic acid (AA)-dependent pathway inhibition in platelet seemed to be specific for TIC caused by multiple injury (MI). The aim of this research was to further study AA-dependent pathway inhibition in platelets in a rat model of TIC caused by MI and to explore its potential mechanisms. METHODS: Sprague-Dawley rat model of TIC caused by MI was established. We used thrombelastography with platelet mapping as a measure of platelet function to assess the inhibitory extent of AA-dependent activation pathway. Flow cytometry was used to determine the expression of activation-dependent granular protein P-selectin (CD62P). In addition, the plasma levels of 6-Keto-prostaglandin F1 alpha (6-Keto-PGF1α), Prostaglandin E2, and Thromboxane B2 were assessed by enzyme-linked immuno sorbent assay. RESULTS: The inhibition rate of AA-dependent pathway after injury was significantly higher than that of control. The maximum amplitude decreased in the MI group, compared with that of control. The percentage of CD62P expression in the MI group was remarkably lower than that of control after AA treatment. The plasma concentrations of 6-Keto-PGF1α and PGE2 increased in the MI group. CONCLUSION: Platelets inhibition was observed in TIC caused by MI at early stage after injury, which might be partially attributed to AA-dependent activation pathway dysfunction. The increase of plasma Prostacyclin and PGE2 levels may contribute to the inhibition process.

Prostaglandin contribution to postexercise hyperemia is dependent on tissue oxygenation during rhythmic and isometric contractions.

The role of prostaglandins (PGs) in exercise hyperemia is controversial. We tested their contributions in moderate intensity forearm exercise, whether their release is oxygen (O2 )-dependent or affected by aging. A total of 12 young (21 ± 1 years) and 11 older (66 ± 2 years) recreationally active men performed rhythmic and isometric handgrip contractions at 60% maximum voluntary contraction for 3 min during air breathing after placebo, after cyclooxygenase (COX) inhibition with aspirin, while breathing 40% O2 and during their combination (aspirin + 40% O2 ). Forearm blood flow (FBF) was recorded with venous occlusion plethysmography (forearm vascular conductance (FVC): FBF/mean arterial pressure). Venous efflux of PGI2 and PGE2 were assessed by immunoassay. Postcontraction increases in FVC were similar for rhythmic and isometric contractions in young and older men, and accompanied by similar increases in efflux of PGI2 and PGE2 . Aspirin attenuated the efflux of PGI2 by 75%-85%, PGE2 by 50%-70%, (p < .05 within group; p > .05 young versus. older), and postcontraction increases in FVC by 22%-27% and 17%-21% in young and older men, respectively (p < .05 within group and young versus. older). In both age groups, 40% O2 and aspirin + 40% O2 caused similar inhibition of the increases in FVC and efflux of PGs as aspirin alone (p < .05 within group). These results indicate that PGs make substantial contributions to the postcontraction hyperemia of rhythmic and isometric contractions at moderate intensities in recreationally active young and older men. Given PGI2 is mainly released by endothelium and PGE2 by muscle fibers, we propose PG generation is dependent on the contraction-induced falls in O2 at these sites.

Microvascular Function Is Impaired after Short-Term Immobilization in Healthy Men.

PURPOSE: We examined whether 2 wk of one-leg immobilization would impair leg microvascular function and to what extent a subsequent period of intense aerobic cycle training could restore function. METHODS: Study participants were healthy young men (n = 12; 20-24 yr of age). Leg microvascular function was determined before the intervention, after the immobilization period, and after a 4-wk exercise training period. Microvascular function was assessed as the vasodilator response to intra-arterial infusion of acetylcholine and sodium nitroprusside and as the vasoconstrictor response to endogenous noradrenaline release induced by tyramine infusion. Vasodilator enzymes as well as prooxidant and antioxidant enzymes were assessed by protein analysis in skeletal muscle samples: endothelial nitric oxide synthase, NADPH oxidase (NOX p67 and NOX gp91), and superoxide dismutase 2 (SOD2). RESULTS: The acetylcholine-induced change in vascular conductance was reduced after the 2 wk of immobilization (P = 0.003), tended to increase (P = 0.061), and was back to baseline levels after the subsequent 4 wk of exercise training. Plasma prostacyclin levels in response to acetylcholine infusion were lower after immobilization than before (P = 0.041). The changes in vascular conductance with sodium nitroprusside and tyramine were similar during all conditions. Skeletal muscle protein levels of endothelial nitric oxide synthase in the experimental leg were unchanged with immobilization and subsequent training but increased 47% in the control leg with training (P = 0.002). NOX p67, NOX gp91, and SOD2 in the experimental leg remained unaltered with immobilization, and SOD2 was higher than preimmobilization after 4 wk of training (P < 0.001). CONCLUSIONS: The study shows that 2 wk of immobilization impairs leg microvascular endothelial function and prostacyclin formation but that 4 wk of intense aerobic exercise training restores the function. The underlying mechanism may reside in the prostacyclin system.

Cotinine inhibits TLR4/NF-κB signaling pathway and improves deep vein thrombosis in rats.

BACKGROUND: The present study was designed to explore the regulatory mechanisms and influences of cotinine on deep vein thrombosis (DVT) in rats via the toll-like receptor 4/nuclear factor κ binding (TLR-4/NF-κB) pathway. METHODS: In this experimental study, 30 SD rats were randomly assigned to control group, sham operation group, model group, cotinine (10 µg/kg) group, and model + cotinine (10 µg/kg) group. The thromboxane B2 (TXB2), 6-keto-PGF1α, plasminogen activator inhibitor (PAI), tissue plasminogen activator (t-PA), TLR4, NF-κB, and p65 mRNA and protein expression and tissue changes were analyzed by ELISA, Hematoxylin-Eosin (HE) staining, RT-PCR, and Western blot. RESULTS: There was no significant difference between the control and sham operation groups (P>0.05). The model and cotinine groups showed significantly higher mRNA and protein levels of TXB2, interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), PAI, TLR-4, and NF-κB, and significantly lower levels of 6-keto-PGF1α and t-PA than the control and sham operation groups (P<0.05), and the model + cotinine group showed significantly higher mRNA and protein levels of TXB2, IL-6 and TNF-α, PAI, TLR-4, and NF-κB and significantly lower levels of 6-keto-PGF1α and t-PA than the model group (P<0.05). CONCLUSION: Cotinine can aggravate thrombus and inflammation in rats with DVT, and the mechanism may be associated with the activation of the TLR-4/NF-κB inflammatory signaling pathway.

Lifelong Physical Activity Determines Vascular Function in Late Postmenopausal Women.

INTRODUCTION: The study evaluated the role of lifelong physical activity for leg vascular function in postmenopausal women (61 ± 1 yr). METHOD: The study design was cross-sectional with three different groups based on self-reported physical activity level with regard to intensity and volume over the past decade: inactive (n = 14), moderately active (n = 12), and very active (n = 15). Endothelial-dependent and smooth muscle-dependent leg vascular function were assessed by ultrasound Doppler measurements of the femoral artery during infusion of acetylcholine (Ach), the nitric oxide (NO) donor sodium nitroprusside and the prostacyclin analog epoprostenol. Thigh muscle biopsies, arterial and venous plasma samples were obtained for assessment of vasodilator systems. RESULTS: The very active group was found to have 76% greater responsiveness to Ach compared with the sedentary group accompanied by 200% higher prostacyclin synthesis during Ach infusion. Smooth muscle cell responsiveness to sodium nitroprusside and epoprostenol was not different between groups. The protein amount of endothelial NO synthase and endogenous antioxidant enzymes in muscle tissue was higher in the very active than the inactive group. The moderately active group had a similar endothelial and smooth muscle cell responsiveness as the inactive group. A secondary comparison with a smaller group (n = 5) of habitually active young (24 ± 2 yr) women indicated that smooth muscle cell responsiveness and endothelial responsiveness are affected by age per se. CONCLUSIONS: This study shows that leg vascular function and the potential to form prostacyclin and NO in late postmenopausal women, is influenced by the extent of lifelong physical activity.

1,25(OH)2D3 improves blood lipid metabolism, liver function, and atherosclerosis by constraining the TGF-ß/Smad signaling pathway in rats with hyperlipidemia.

1,25(OH)2D3 has already been reported to function in some diseases. However, its role in hyperlipidemia (HLP) remains unknown. This study aims to investigate the effect of 1,25(OH)2D3 on HLP rats. Rat models were established by high-fat diet feeding, perfusion of different doses of 1,25-(OH)2D3 and injection of TGF-ß1 siRNA. Whole blood viscosity, plasma viscosity, hematocrit, and erythrocyte aggregation index were detected, together with levels of biochemical indexes, 6-keto-PGF1α, and TXB2 in serum. Levels of oxidative stress indexes and inflammatory factors in serum and liver tissues were determined. TGF-ß1 and Smad3 expression in serum, liver tissues, and aorta was detected. 1,25(OH)2D3 lowered HLP-induced rise of whole blood viscosity, red blood cell aggregation index, plasma viscosity, and hematocrit, TC, TG, LDL-C, apoB, ALT, AST, TXB2, MDA, IL-1ß, TNF-α, and increased HLP-induced decrease of HDL-C, apoAI, 6-keto-PGF1α, SOD, GSH-Px, CAT, and T-AOC. TGF-ß1 and Smad3 expression in serum, liver tissue, and aorta of 1,25(OH)2D3-treated rats reduced. High 1,25(OH)2D3 dose and inhibited TGF-ß/Smad signaling pathway alleviated lipid metabolism, liver function, and atherosclerotic injury in HLP rats. Our study found that 1,25(OH)2D3 improves blood lipid metabolism, liver function, and atherosclerosis injury by constraining the TGF-ß/Smad signaling pathway in rats with HLP.

Maternal vitamin D deficiency increases the thromboxane/prostacyclin ratio through alterations in the one-carbon cycle in Wistar rats.

This study aims to test the hypothesis that vitamin D deficiency can influence long-chain polyunsaturated fatty acid metabolism through alterations in the one-carbon cycle. Wistar rats (n = 8 per group) were given either a control (1,000 IU D3/kg diet) or a vitamin D deficient (VDD) (0 IU D3/kg diet) diet from pre-pregnancy to delivery. On day 20 of gestation, pregnant female rats were delivered by C-section to collect placenta and blood. VDD group demonstrated high serum parathyroid hormone, low serum phosphate, low plasma folate, higher plasma homocysteine, and higher plasma malondialdehyde levels (P < 0.05 for all) as compared to control. Lower protein levels of placental cystathionine-ß-synthase enzyme (P < 0.05) were observed in the VDD group as compared to control. VDD group demonstrated higher placental mRNA levels of the enzymes phospholipase A2 and cyclooxygenase-2 (P < 0.05 for both) as compared to control. Protein levels of the enzymes phospholipase A2 and cyclooxygenase-2 were lower (P < 0.05 for both) in the VDD group as compared to the control group. The ratio of thromboxane B2 and 6-keto prostaglandin F1α in serum was higher (P < 0.05) in the VDD group as compared to control; although the serum levels of 6-keto prostaglandin F1α and thromboxane B2 were similar in both the groups. Our findings suggest that increased oxidative stress due to maternal vitamin D deficiency results in the imbalance between the vasoconstrictor (thromboxane B2 ) and vasodilator (6-keto prostaglandin F1α ) eicosanoids, which may lead to endothelial dysfunction and poor pregnancy outcome. © 2019 BioFactors, 45 (4):548-555, 2019.

Effect of Different Doses of Acetylsalicylic Acid on the Antithrombotic Activity of Clopidogrel in a Mouse Arterial Thrombosis Model.

Objective- Dual-antiplatelet therapy with acetylsalicylic acid and a P2Y12 antagonist, such as clopidogrel, is the standard of care for acute coronary syndromes. However, the drugs have divergent effects on the formation of cAMP, an inhibitory second messenger. Thus, by inhibiting the synthesis of prostacyclin, acetylsalicylic acid reduces cAMP formation, whereas clopidogrel potentiates it. Therefore, with higher doses of acetylsalicylic acid, the potentiation of cAMP production by clopidogrel may be attenuated, which could limit the antithrombotic potential of the drug combination. The purpose of this study was to examine this possibility in vivo. Approach and Results- Mice were given oral acetylsalicylic acid at varying doses, oral clopidogrel (5 mg/kg body weight), or both. At doses of 0.15 and 0.6 mg/kg, acetylsalicylic acid inhibited arachidonic acid-induced platelet aggregation, but only 0.6 mg/kg acetylsalicylic acid, or higher, decreased the plasma levels of 6-keto-prostaglandin-F1α, the stable metabolite of prostacyclin. When given with clopidogrel, laser injury-induced arterial thrombi were significantly larger with the 0.6 mg/kg dose of acetylsalicylic acid than with the 0.15 mg/kg dose. Thrombi in mice treated with clopidogrel and the 0.15 mg/kg dose of acetylsalicylic acid were smaller than in mice treated with clopidogrel alone, suggesting that acetylsalicylic acid can add to the antithrombotic effect of clopidogrel but that higher doses of acetylsalicylic acid blunt the antithrombotic effect of clopidogrel. Conclusions- These findings support the use of lower, prostacyclin-preserving, doses of acetylsalicylic acid in conjunction with clopidogrel.

Mahuang decoction mitigates airway inflammation and regulates IL-21/STAT3 signaling pathway in rat asthma model.

ETHNOPHARMACOLOGICAL RELEVANCE: Nowadays, bronchial asthma is still a severe disease threatening human health, and it is incumbent upon us to seek effective therapeutic drugs. Mahuang decoction (MHD), a classic famous Chinese prescription, has been used for thousands of years to prevent phlegm from forming, stop coughing and relieve asthma, but the relevant mechanism has not been thoroughly clarified. This study aims to investigate the anti-airway inflammation effect of MHD and the possible molecular mechanism underlying IL21/STAT3 signaling pathway, so as to provide guidance for the treatment of MHD on bronchial asthma. MATERIALS AND METHODS: Specific pathogen free SD rats were randomly divided into 6 groups: normal control group, model group, positive group (Compound methoxyphenamine), MHD-treated groups at doses of 10 ml/kg, 5 ml/kg and 2.5 ml/kg, 10 rats in each group. Except for the normal control group, rats in other groups were sensitized with ovalbumin via introperitoneal injection and challenged with ovalbumin inhalation to trigger asthma model. At 24 h after the last excitation, bronchoalveolar lavage fluid (BALF) of every rat was drawn and the number of inflammatory cells was analyzed using cell counting method. ELISA method was performed to determine the concentrations of TXB2, 6-keto-PGF1α, MMP-9, TIMP-1, IL-2, IL-4, IL-5 and TNF-α in rat serum. The protein expressions of IL-21, IL-21R, STAT3 and p-STAT3 in murine pulmonary tissues were assessed with western blotting analysis. RESULTS: Compared with the control group, the airway wall and airway smooth muscle of murine pulmonary tissues significantly thickened and massive inflammatory cells infiltration occurred around the bronchus in the model group, and the cell counts of WBC and EOS in BALF were also apparently increased, which indicated the rat asthma model was successfully established. MHD or Compound methoxyphenamine not only alleviated the pulmonary inflammatory pathological damages, but also down- regulated the numbers of WBC and EOS in BALF. What's more, the levels of TXB2, MMP-9, TIMP-1, ILs-(2, 4, 5) and TNF-α in rat serum were lessened by the treatment of MHD. In western blotting analysis, treatment with 10 ml/kg or 5 ml/kg MHD markedly declined the increased protein expressions of IL-21, IL-21R, STAT3 and p-STAT3 in lung tissues of asthmatic rats to normal level. CONCLUSION: MHD intervention demonstrated a strong inhibitory action on the secretion of inflammatory mediators as well as the inflammatory cell infiltration in pulmonary tissues of asthmatic rats, and also depressed the protein expressions of IL-21, IL-21R, STAT3 and p-STAT3 in pulmonary tissues. MHD effectively mitigates airway inflammation and regulates the IL-21/STAT3 signaling pathway in rat asthma model.

Vascular Nitric Oxide-Superoxide Balance and Thrombus Formation after Acute Exercise.

INTRODUCTION: An acute bout of strenuous exercise in humans results in transient impairment of nitric oxide (NO)-dependent function, but it remains unknown whether this phenomenon is associated with increased risk of thrombotic events after exercise. This study aimed to evaluate effects of a single bout of exhaustive running in mice on the balance of vascular NO/reactive oxygen species production, and on thrombogenicity. METHODS: At different time points (0, 2, and 4 h) after exercise and in sedentary C57BL/6 mice, the production of NO and superoxide (O2) in aorta was measured by electron paramagnetic resonance spin trapping and by dihydroethidium/high-performance liquid chromatography-based method, respectively, whereas collagen-induced thrombus formation was analyzed in a microchip-based flow-chamber system (total thrombus-formation analysis system). We also measured pre- and postexercise plasma concentration of nitrite/nitrate and 6-keto-PGF1α. RESULTS: An acute bout of exhaustive running in mice resulted in decreased production of NO and increased production of O2 in aorta, with maximum changes 2 h after completion of exercise when compared with sedentary mice. However, platelet thrombus formation was not changed by exercise as evidenced by unaltered time to start of thrombus formation, capillary occlusion time, and total thrombogenicity (area under the flow pressure curve) as measured in a flow-chamber system. Strenuous exercise increased the plasma concentration of nitrite but did not affect nitrate and 6-keto-PGF1α concentrations. CONCLUSION: An acute bout of strenuous exercise in mice reduced NO and in parallel increased O2 production in aorta. This response was most pronounced 2 h after exercise. Surprisingly, the reduced NO and increased O2 production in mice after exercise did not result in increased platelet-dependent thrombogenicity. These results show that transient reduction in NO bioavailability does not modify thromboresistance in healthy mice after exercise.

Low-dose Aspirin Inhibits Cardiac Sympathetic Activation and Vagal Withdrawal Response to Morning Rising.

Aspirin is known to interfere with platelet function and can protect individuals at risk of sudden death. However, this property of aspirin is less defined for cardiac autonomic activity. We assessed pulse rate variability by spectral analysis and measured plasma eicosanoid levels before and after administration of 81-mg aspirin to 12 healthy subjects over a 60-degree head-up tilt test in the morning. In upright posture, low-dose aspirin decreased both the normalized unit value of low-frequency (normalized LF) power (mean ± SD, 82.5 ± 4.5 vs. 77.5 ± 6.5 nu, P = 0.01) and LF/HF ratio (6.0 ± 2.1 vs. 4.7 ± 2.7, P = 0.02) and augmented the normalized unit value of high-frequency power (15.0 ± 4.4 vs. 19.8 ± 6.4 nu, P = 0.004). It simultaneously upregulated plasma 6-keto-PGF1α level (13.4 ± 6.8 vs. 19.7 ± 12.8 pg/mL, P = 0.04) and inhibited plasma thromboxane B2 (TXB2) level (11.6 ± 7.3 vs. 6.3 ± 4.2 pg/mL, P = 0.003). In the upright posture, both before and after aspirin, there was a significant direct correlation between plasma TXB2 levels and the normalized LF power (r = 0.42, P = 0.04) as well as between the plasma TXB2/6-keto-PGF1α ratio and the normalized LF power (r = 0.50, P = 0.01). Administration of low-dose aspirin in healthy people inhibits cardiac sympathetic activation and vagal withdrawal response to morning rising through an alternation of the TXA2/PGI2 balance.

Prostacyclin, thromboxane and glomerular filtration rate are abnormal in sickle cell pregnancy.

BACKGROUND: Pregnancy increases the risk of morbidity and mortality in sickle cell disease. We previously showed pregnant women with sickle cell disease to have a relatively low plasma renin concentration in late pregnancy, associated with a lack of the expected plasma volume expansion. We hypothesized this to be due to increased systemic vascular resistance through an imbalance between the vasodilator prostacyclin and vasoconstrictor thromboxane, associated with decreased glomerular filtration rate (GFR). OBJECTIVE: To compare estimated prostacyclin, thromboxane and GFR in non-pregnant and pregnant women with hemoglobin SS (HbSS) and AA (HbAA). STUDY DESIGN: Four groups of 20 normotensive, nulliparous women were studied in Lagos, Nigeria: pregnant HbSS or HbAA women at 36-40 weeks gestation; non-pregnant HbSS and HbAA controls. We measured stable metabolites of prostacyclin and thromboxane A2 by enzyme-linked immunosorbent assay; GFR using the Cockcroft-Gault equation. Data analysis was by independent (Student's) t-test or Mann-Whitney U test for comparisons between any two groups of continuous variables, univariate ANOVA for multiple groups and Pearson's correlation coefficient for degree of association between variables. RESULTS: HbSS women had lower serum 6-keto-PGF1α concentrations than HbAA, whether pregnant or non-pregnant (P<0.001; P<0.004 respectively). Conversely, pregnant HbSS women had higher serum TxB2 (P<0.001); non-pregnant HbSS women had non-significantly higher TxB2 concentrations. The 6-keto-PGF1α:TxB2 ratio was markedly increased (pro-vasodilatory) in HbAA pregnancy (P<0.001) but reduced in HbSS pregnancy (P = 0.037). GFRs (mL/min) were higher in non-pregnant HbSS than HbAA (P<0.008) but only marginally raised in HbSS women in late pregnancy (P = 0.019) while markedly raised in HbAA pregnancy (P<0.001). CONCLUSION: The lower ratio of prostacyclin-thromboxane metabolites in HbSS pregnancy may indicate endothelial damage and an increased tendency to vasoconstriction and clotting. If confirmed by subsequent longitudinal studies, interventions to increase prostacyclin and reduce thromboxane, such as low dose aspirin, may be potentially useful in their management.

Therapeutic effects of flurbiprofen axetil on mesenteric traction syndrome: randomized clinical trial.

BACKGROUND: This study aimed to reveal the appropriate timing for the intravenous administration of flurbiprofen axetil for preventing mesenteric traction syndrome (MTS), caused by prostacyclin release. METHODS: In this prospective, randomized, clinical study, forty-five patients who were undergoing elective surgery for colorectal cancer via laparotomy were enrolled. Patients were randomly divided into 3 groups: a preoperative group (n = 16) receiving flurbiprofen axetil directly before surgery; a post-MTS group (n = 14) receiving following MTS onset; and a control group (n = 15) who were not administered flurbiprofen axetil. 6-keto-PGF1α, a stable metabolite of prostacyclin, levels were measured and mean blood pressures were recorded. RESULTS: In the preoperative group, 6-keto-PGF1α levels did not increase, blood pressure levels did not decrease, and no facial flushing was observed. In both the post-MTS and control groups, 6-keto-PGF1α levels increased markedly after mesenteric traction and blood pressure decreased significantly. The post-MTS group exhibited a faster decreasing trend in 6-keto-PGF1α levels and quick restore of the mean blood pressure, and the use of vasopressors and phenylephrine were lower than that in the control group. CONCLUSIONS: Even therapeutic administration of flurbiprofen axetil after the onset of MTS has also effects on MTS by suppressing prostacyclin production. TRIAL REGISTRATION: Clinical trial number: UMIN000009111 . (Registered 14 October 2012).

Antithrombotic effect and mechanism of Rubus spp. Blackberry.

The compounds of Rubus spp. Blackberry (RSB) were isolated and identified by a bioassay-guided method, and their antithrombotic effects and mechanism were investigated with the acute blood stasis rat model. The RSB extract was evaluated by activated partial thromboplastin time (APTT), thrombin time (TT), prothrombin time (PT), and fibrinogen (FIB) assays in vitro. Results indicated that RSB extract exhibited anticoagulant activity. In addition to compounds 1 and 6, the other compounds also exhibited anticoagulant activity in vitro. Therefore, the in vivo antithrombosis effects of RSB extract were investigated by measuring whole blood viscosity (WBV), plasma viscosity (PV), APTT, PT, TT, and FIB. Meanwhile, the levels of thromboxane B2 (TXB2), 6-keto prostaglandin F1α (6-keto-PGF1α), endothelial nitric oxide synthase (eNOS) and ET-1 (endothelin-1) were measured. Results suggested that RSB extract had inhibitory effects on thrombus formation, and its antithrombotic effects were associated with the regulation of vascular endothelium active substance, activation of blood flow and an anticoagulation effect.

Potential Biomarkers for the Diagnosis of Angiotensin-Converting Enzyme Inhibitor-Induced Angioedema.

BACKGROUND: Angiotensin-converting enzyme inhibitor-induced angioedema (ACEi-AE) is the most frequent drug-induced angioedema. The aim of this study was to evaluate potential biomarkers for the detection of the risk to develop an ACEi-AE. METHODS: Adult patients who started antihypertensive treatment with ramipril were included and followed up for 4-6 weeks. At baseline, 3 days, and 4-6 weeks after onset of therapy, blood samples were obtained. RESULTS: Twenty-four patients could be enrolled. The thromboxane values were very heterogeneous, and none of the group differences observed was statistically significant. The values obtained for 6-keto-prostaglandin F1α (6-keto-PGF1α) showed a statistically significant increase with 10 mg/day doses under ramipril therapy. CONCLUSIONS: In this small patient population, it could be shown that determination of 6-keto-PGF1α is feasible. It may prove to be a valuable blood marker for assessing the risk of developing ACEi-AE.

Effects of a single bout of strenuous exercise on platelet activation in female ApoE/LDLR-/- mice.

Strenuous physical exercise leads to platelet activation that is normally counterbalanced by the production of endothelium-derived anti-platelet mediators, including prostacyclin (PGI2) and nitric oxide (NO). However, in the case of endothelial dysfunction, e.g. in atherosclerosis, there exists an increased risk for intravascular thrombosis during exercise that might be due to an impairment in endothelial anti-platelet mechanisms. In the present work, we evaluated platelet activation at rest and following a single bout of strenuous treadmill exercise in female ApoE/LDLR-/- mice with early (3-month-old) and advanced (7-month-old) atherosclerosis compared to female age-matched WT mice. In sedentary and post-exercise groups of animals, we analyzed TXB2 generation and the expression of platelet activation markers in the whole blood ex vivo assay. We also measured pre- and post-exercise plasma concentration of 6-keto-PGF1α, nitrite/nitrate, lipid profile, and blood cell count. Sedentary 3- and 7-month-old ApoE/LDLR-/- mice displayed significantly higher activation of platelets compared to age-matched wild-type (WT) mice, as evidenced by increased TXB2 production, expression of P-selectin, and activation of GPIIb/IIIa receptors, as well as increased fibrinogen and von Willebrand factor (vWf) binding. Interestingly, in ApoE/LDLR-/- but not in WT mice, strenuous exercise partially inhibited TXB2 production, the expression of activated GPIIb/IIIa receptors, and fibrinogen binding, with no effect on the P-selectin expression and vWf binding. Post-exercise down-regulation of the activated GPIIb/IIIa receptor expression and fibrinogen binding was not significantly different between 3- and 7-month-old ApoE/LDLR-/- mice; however, only 7-month-old ApoE/LDLR-/- mice showed lower TXB2 production after exercise. In female 4-6-month-old ApoE/LDLR-/- but not in WT mice, an elevated pre- and post-exercise plasma concentration of 6-keto-PGF1α was observed. In turn, the pre- and post-exercise plasma concentrations of nitrite (NO2-) and nitrate (NO3-) were decreased in ApoE/LDLR-/- as compared to that in age-matched WT mice. In conclusion, we demonstrated overactivation of platelets in ApoE/LDLR-/- as compared to WT mice. However, platelet activation in ApoE/LDLR-/- mice was not further increased by strenuous exercise, but was instead attenuated, a phenomenon not observed in WT mice. This phenomenon could be linked to compensatory up-regulation of PGI2-dependent anti-platelet mechanisms in ApoE/LDLR-/- mice.

Microvascular pathological features and changes in related injury factors in a rat acute blood stasis model.

OBJECTIVE: To examine the microvascular pathological characteristics and changes in related injury factors in a rat model of acute blood stasis. METHODS: A total of 75 Sprague-Dawley rats were divided randomly and equally into a control group and four experimental groups assessed at different times after the induction of stasis (0, 1, 3 or 6 h after stasis) (n = 15). The acute blood stasis model was established through rat tail-vein injection of high-molecular-weight dextran. After Electrocardiograph (ECG) detection at predetermined times (0, 1, 3 and 6 h after induction of stasis), the rats were sacrificed and blood and cardiac samples were harvested for analysis. Hematoxylin-eosin (HE) staining and transmission electron microscopy were used for histopathological detection; an enzyme linked immunosorbent assay (ELISA) was used to detect thromboxane B2 (TXB2) and 6-keto-prostaglandin F1α (6-Keto-PGF1α) concentrations; a real-time polymerase chain reaction (PCR) reaction system was used to detect intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule1 (VCAM-1) mRNA expression; western blotting was used to detect vascular endothelial cadherin (VE-cadherin) protein expression. RESULTS: The ST segment in the ECG showed gradual elevation after induction of stasis and continued elevation at a high level at 3 and 6 h. The HE staining showed changes in myocardial cell necrosis and tissue dissociation after the induction of stasis, along with inflammatory infiltration. Results of transmission electron microscopy showed immediate changes in blood stasis and lumen occlusion in the microvasculature, along with endothelial cell swelling. After the induction of stasis, TXB2 concentrations gradually increased while 6-Keto-PGF(1α) concentrations were immediately significantly reduced. The TXB(2)/6-Keto-PGF(1α) ratio was maintained at a high level. ICAM-1 mRNA expression showed an unstable elevation while VCAM-1 mRNA expression was significantly reduced after the induction of stasis. Compared with the control group, VE-cadherin protein expression increased at 0 and 3 h after the induction of stasis, while no change occurred at 1 and 6 h. CONCLUSION: The pathological manifestations of acute blood stasis are microvascular blood retention, lumen stenosis and even occlusion. The condition is also called "blood coagulation and weep" in Traditional Chinese Medicine. The blood stasis model resulted in the injury and necrosis of endothelial cells and cardiomyocytes, along with the presence of an imbalance of vasomotor factor levels, platelet activation, and increases in the expression of adhesion molecules and endothelial barrier dysfunction, which corresponds to "blood failed to nourish" in Traditional Chinese Medicine.

Effects of astaxanthin on blood coagulation, fibrinolysis and platelet aggregation in hyperlipidemic rats.

CONTEXT: Astaxanthin (ASTX) is a xanthophyll carotenoid that reduces hemostasis in hyperlipidemic organisms. Its antihemostatic mechanisms remain unclear. OBJECTIVE: The effects of ASTX on coagulation, the fibrinolytic system and platelet aggregation were investigated in hyperlipidemic rats. MATERIALS AND METHODS: Different doses of ASTX (5, 10 and 30 mg/kg/day, p.o.) were administered for four weeks to high-fat diet-induced hyperlipidemic rats. Serum lipid and lipoprotein levels were measured with an automatic biochemical analyzer. The prothrombin time (PT), activated partial thromboplastin time (APTT) and maximum platelet aggregation rate (MAR) were determined by a coagulation analyzer. The activities of the tissue-type plasminogen activator (t-PA), type-1 plasminogen activator inhibitor (PAI-1) and endothelial nitric oxide synthase (eNOS), as well as the levels of thromboxane B(2) [TXB(2)], 6-keto prostaglandin F(1α) [6-keto-PGF(1α)] and platelet granule membrane protein (GMP-140), were measured with enzyme-linked immunosorbent assay kits. Gene and protein expression levels were analyzed by reverse transcriptase polymerase chain reaction and Western blot, respectively. RESULTS: ASTX (30 mg/kg) treatment in hyperlipidemic rats reduced serum TG (0.58 ± 0.14 versus 1.12 ± 0.24 mmol/L), serum TC (1.77 ± 0.22 versus 2.24 ± 0.21 mmol/L), serum LDL-C (1.13 ± 0.32 versus 2.04 ± 0.48 mmol/L), serum MDA (69%), plasma MAR (55%), serum TXB2/6-keto-PGF1α (34%) and serum GMP-140 levels (25%), plasma PAI-1 activity (48%) and downregulated the mRNA (33%) and protein (23%) expression of aorta eNOS, the mRNA (79%) and protein (72%) expression levels of aorta PAI-1. However, ASTX (30 mg/kg/d) treatment increased serum SOD activity (2.1 fold), serum GPx activity (1.8 fold), plasma PT (1.3 fold), plasma APTT (1.7 fold), serum NO (1.4-fold), serum 6-keto-PGF1α (1.3 fold). CONCLUSIONS: ASTX reduced blood coagulation and platelet aggregation and promoted fibrinolytic activity in hyperlipidemic rats. These activities were closely correlated with ASTX, maintaining the balance of t-PA/PAI-1, NO/ROS and TXA2/PGI2 in vivo.

Effects of chronic nitric oxide synthase inhibition on V'O2max and exercise capacity in mice.

Acute inhibition of NOS by L-NAME (Nω-nitro-L-arginine methyl ester) is known to decrease maximal oxygen consumption (V'O2max) and impair maximal exercise capacity, whereas the effects of chronic L-NAME treatment on V'O2max and exercise performance have not been studied so far. In this study, we analysed the effect of L-NAME treatment, (LN2 and LN12, respectively) on V'O2max and exercise capacity (in maximal incremental running and prolonged sub-maximal incremental running tests), systemic NO bioavailability (plasma nitrite (NO2-) and nitrate (NO3-)) and prostacyclin (PGI2) production in C57BL6/J mice. Mice treated with L-NAME for 2 weeks (LN2) displayed higher V'O2max and better running capacity than age-matched control mice. In LN2 mice, NO bioavailability was preserved, as evidenced by maintained NO2- plasma concentration. PGI2 production was activated (increased 6-keto-PGF1α plasma concentration) and the number of circulating erythrocytes (RBC) and haemoglobin concentration were increased. In mice treated with L-NAME for 12 weeks (LN12), NO bioavailability was decreased (lower NO2- plasma concentration), and 6-keto-PGF1α plasma concentration and RBC number were not elevated compared to age-matched control mice. However, LN12 mice still performed better during the maximal incremental running test despite having lower V'O2max. Interestingly, the LN12 mice showed poorer running capacity during the prolonged sub-maximal incremental running test. To conclude, short-term (2 weeks) but not long-term (12 weeks) treatment with L-NAME activated robust compensatory mechanisms involving preservation of NO2- plasma concentration, overproduction of PGI2 and increased number of RBCs, which might explain the fully preserved exercise capacity despite the inhibition of NOS.