Thromboxane Synthetase Inhibitor Research Articles

Semi-Mechanistic Modeling of HY-021068 Based on Irreversible Inhibition of Thromboxane Synthetase.

Background: HY-021068 [4-(2-(1H-imidazol-1-yl) ethoxy)-3-methoxybenzoate], developed by Hefei Industrial Pharmaceutical Institute Co., Ltd. (Anhui, China), is a potential thromboxane synthetase inhibitor under development as an anti-platelet agent for the treatment of stroke. A semi-mechanistic pharmacokinetic/pharmacodynamic (PK/PD) model was developed to characterize the PK of HY-021068 and its platelet aggregation inhibitory effect in beagle dogs. Method: Beagle dogs received single oral administration of 2.5 mg/kg HY-021068 or consecutively oral administration of 5 mg/kg HY-021068 once daily for 7 days. The plasma concentration of HY-021068 and the platelet aggregation rate (PAR) were determined by liquid chromatography tandem-mass spectrometry (LC‐MS/MS) assay and a photometric method, respectively. The PK/PD data was sequentially fitted by Phoenix NLME. The PK/PD parameters of HY-021068 in beagle dogs were estimated by 2.5 and 5 mg/kg dosing on the 1st day, and then used to simulate the PAR of HY-021068 on the 7th day after 5 mg/kg dosing daily. Result: A one-compartment model with saturable Michaelis-Menten elimination was best fitted to the PK of HY-021068. A mechanistic PD model based on irreversible inhibition of thromboxane synthetase was constructed to describe the relationship between plasma concentration of HY-021068 and PAR. Diagnostic plots showed no obvious bias. Visual predictive check confirmed the stability and reliability of the model. Most of PK/PD observed data on the 7th day after 5 mg/kg dosing fell in the 90% prediction interval. Conclusion: We established a semi-mechanistic PK/PD model for characterizing the PK of HY-021068 and its anti-platelet effect in beagle dogs. The model can be used to predict the concentration and PAR under different dosage regimen of HY-021068, and might be served as a reference for dose design in the future clinical studies.

Phase I Trial of Pyragrel, a Novel Thromboxane Synthetase Inhibitor, to Evaluate the Safety, Tolerability, and Pharmacokinetics in Healthy Volunteers.

Background and Objective: Inhibition of thrombosis and platelet aggregation through a thromboxane synthetase inhibitor proved to be an effective and promising treatment for cardiovascular and/or cerebrovascular disease (CCVD) patients. This phase I study evaluated the safety, tolerability, and pharmacokinetics of sodium pyragrel, a novel thromboxane A2 synthetase inhibitor, in healthy volunteers. Methods: A total of 84 healthy Chinese volunteers were enrolled in the study and randomized into one of five dosing regimens of intravenous pyragrel, which were single ascending dose (30 to 300 mg), multiple doses (pyragrel 180 mg once daily on Day 1 and Day 6, twice daily from Day 2 to Day 5), 3×3 Latin square crossover (60, 120, 240 mg), and a continuous dose (360 mg in 24 h), respectively. Plasma concentrations were determined using HPLC-MS/MS. Pharmacokinetics parameters were calculated with non-compartment analysis. Results: The maximum plasma concentrations of pyragrel were essentially reached at the end of the 3 h infusion. The pharmacokinetic process of pyragrel and two main metabolites (BBS and BJS) is linear over the 30–300 mg dose range, with no significant accumulation on multiple doses. The urinary excretion of pyragrel accounted for more than 70% of the total drug amount. Preliminary pharmacodynamic results demonstrated that the production of urinary 11-D-HTXB2 was time- and dose-dependently inhibited by single i.v. dose of pyragrel. Conclusions: Pyragrel was well tolerated after single ascending doses up to 300 mg, multiple doses of 180 mg, and continuous administration of 360 mg within 24 h. No drug-related, serious adverse drug reactions occurred during the five-part study. The most common pyragrel-related adverse events (AEs) were total bilirubin (TB)/direct bilirubin (DB) elevations with a relatively low incidence rate and seemed to be dose independent. Given the acceptable safety and appropriate pharmacokinetic properties of sodium pyragrel proven in this study, continued clinical development is warranted. The study was registered at http://www.chictr.org.cn (ChiCTR-IID-16010159).

Ozagrel for Postoperative Management of Aneurysmal Subarachnoid Hemorrhages.

A number of pharmacological agents have been tried to circumvent the problem of delayed cerebral ischemia (DCI) with ozagrel sodium being one such agent aimed at the prevention of DCI. Ozagrel is an inhibitor of thromboxane synthetase. It has anti-platelet aggregation action and it dilates vessels. Ozagrel was not available outside Japan till recently. It is available now in India and we had the opportunity to use it among patients with aneurysmal subarachnoid hemorrhage (SAH). To analyse the results of ozagrel administration for patients with aneurysmal SAH. Tertiary care neurosurgical center. Retrospective analysis of the outcomes of patients who received ozagrel after microsurgical cllipping of aneurysm and comparison with a control grpup who received treatment as usual. The t-test (two-tailed), Chi-square test, and Mann-Whitney U-test asymptomatic significance (two-tailed), were used respectively for continuous, categorical, and ordinal variables. The significance was determined at P = 0.05 level. A total of 106 patients underwent surgical clipping of their ruptured intracranial aneurysms over a period of 22 months. Forty two (39.6%) patients received ozagrel, and 62 (60.4%) received the standard treatment. Ozagrel was started at a median of one [interquartile range (IQR) 0.75] day after the surgery, and was given for a median of five (IQR 5) days after the surgery. There was no difference in age, postictal days, World Federation Neurosurgical Society grade, Fisher grade, and the size of ruptured aneurysm in patients who received ozagrel compared to the patients who did not receive ozagrel. Of the 42 patients who received ozagrel, 30 patients (71.4%) had preoperative angiographic vasospasm which improved after the administration of ozagrel. Fifteen (35.5%) patients who received ozagrel developed delayed cerebral ischemia compared to only 11 (17.2%) patients who did not receive ozagrel. Thirty-six (85.7%) patients who received ozagrel had favorable outcome at discharge compared to 52 (81.3%) patients who did not receive ozagrel. No adverse event was observed with ozagrel therapy. At 3-month follow-up, 37 patients (88.1%) who received ozagrel had favorable outcomes against 53 patients (82.8%) who did not receive ozagrel. Ozagrel may be a useful drug in the armamentarium to treat vasospasm after aneurysmal SAH. A future multicenter large cohort study may validate the findings of our study.

N2 ameliorates neural injury during experimental ischemic stroke via the regulation of thromboxane A2 production

Thromboxane A2 (TXA2) promotes ischemic stroke injury and has strong effects in vascular contraction and vascular endothelial cell dysfunction. Agents that reduce TXA2 production have potential for ameliorating neural injury in ischemic stroke. Thromboxane synthetase (TXS) is essential for TXA2 production, and TXS inhibitors have been developed as drugs for the prevention and treatment of stroke. However, ozagrel, a typical TXS inhibitor currently in clinical use, must be delivered via intravenous injection (I.V.). N2, 4-(2-(1H-imidazol-1-yl) ethoxy)-3-methoxybenzoate, is a potential thromboxane synthetase (TXS) inhibitor, which is being developed as an orally available formulation. The aim of this study was to investigate the effects of N2 on focal cerebral ischemia–reperfusion injury and related mechanisms. Neurological deficits, a Y-maze test and infarct volume were measured to evaluate the effects of N2 post-treatment on middle cerebral artery occlusion (MCAO)-induced ischemia/reperfusion (I/R) injury in rats. Furthermore, the influence of N2 on U46619-induced rat aorta contraction was investigated ex vivo. Moreover, we investigated the protective effects of N2 on rat brain microvessel endothelial cells (RBMECs) in hypoxia/deoxygenating (H/R) induced by Na2S2O4 in vitro. Cell viability and TXA2 biosynthesis were measured by 3-(4, 5-dimethylthiazol-2-yl)- 195 2, 5-diphenyltetrazolium bromide (MTT) and enzyme-linked immunosorbent assay (ELISA) assays, respectively. The results showed that N2 treatment effectively improves performance in neurological deficit and the Y-maze test and reduces the infarct volume in I/R rats. U46619-induced rat aorta contraction was inhibited by N2 ex vivo. Furthermore, N2 incubation improved the morphology of RBMECs, increased cell viability, and suppressed TXA2 production by inhibiting TXS during H/R damage.In summary, this study demonstrated that N2 was neural protective in focal cerebral I/R injury, which might be associated with the effects of N2 on endothelium protection and vascular contraction inhibition. In depth, the mechanisms underlying this phenomenon might be the influence of N2 on TXA2 production targeting TXS.

Pharmacological actions of ICI 180080, a novel thromboxane receptor antagonist.

ICI 180080 (5(Z)-7-[2,2-dimethyl-4-(2-hydroxyphenyl)-1,3-dioxan-cis-5-yl] heptenoic acid) potently inhibited contractions of rat and rabbit aortae and guinea-pig trachea elicited by 11,9-epoxymethano PGH2 (U-46619). This antagonism was selective because contractions of aortae to noradrenaline and 5-hydroxytryptamine and trachea to histamine were not antagonized by ICI 180080. Schild analysis of data obtained from experiments on rabbit aortae indicated that this thromboxane receptor antagonism was competitive (pA2 = 7.50, slope = 1.07). Addition of ICI 180080 to human platelet-rich plasma caused dose-related inhibition of U-46619-induced platelet aggregation. This modification of platelet aggregation was not associated with inhibition of thromboxane synthetase, cyclo-oxygenase or lipoxygenase. ICI 180080 did not modify the primary phase of ADP-induced aggregation of human platelets neither did it affect the platelet inhibitory activity of prostacyclin. When dosed orally to anaesthetized guinea-pigs, ICI 180080 (5-50 mg kg-1) caused dose-related inhibition of U-46619-evoked bronchoconstriction. We conclude that ICI 180080 is a potent, selective, competitive, orally active thromboxane antagonist.

The Pharmacokinetics and Pharmacodynamics of a New Thromboxane Synthetase Inhibitor, 6-(1-Imidazolylmethyl)-5,6,7,8-tetrahydronaphthalene-2-carboxylic acid (DP-1904) in Man after Repeated Oral Doses

The pharmacokinetics of DP-1904, a new potent and selective thromboxane synthetase inhibitor, and its effects on ex-vivo prostanoid formation have been studied in groups of Japanese normal male volunteers, who received repeated oral doses of 200 mg every 12 h for 4 doses, or 400 mg every 24 h for 2 doses, or 200 mg every 12 h for 14 doses. The drug was well tolerated by all subjects without evidence of adverse reactions. Repeated administration showed no significant changes in half-lives, tmax values, cmax values and AUC values. DP-1904 did not exhibit time-dependent kinetics. Its plasma levels were lower than the quantifiable level (50 ng mL-1) at 12 h after each dose. These data suggest no significant accumulation of DP-1904 in normal volunteers. DP-1904 reduced the serum thromboxane B2 by about 80% during the medication, the serum concentrations returning to about 44, 75 and 20% of the predrug control values at 36 h after the last 200 mg doses and 48 h after the last 400 mg dose.

The pharmacokinetics and pharmacodynamics of a new thromboxane synthetase inhibitor, 6-(1-imidazolylmethyl)-5,6,7,8-tetrahydronaphthalene-2-carboxylic acid (DP-1904), in man after single oral administration.

The pharmacokinetics of DP-1904, a new potent and selective thromboxane synthetase inhibitor and its effects on ex-vivo prostanoid formation were studied in Japanese normal male volunteers, who received orally a single 10, 20, 50, 100, 200, 400 or 800 mg dose. The drug was well tolerated by all subjects without evidence of any adverse reactions. The absorption of DP-1904 from gastro-intestinal tract was rapid. After oral doses of 10-800 mg of the drug given to volunteers in the fasted state, the mean maximum drug concentrations in plasma (Cmax) (mean +/- s.e., n = 5) of 0.215 (+/- 0.041), 0.399 (+/- 0.037), 1.47 (+/- 0.22), 2.86 (+/- 0.22), 4.66 (+/- 0.58), 7.28 (+/- 0.72) and 16.9 (+/- 2.6) micrograms mL-1 were reached within 1 h. DP-1904 concentrations declined monophasically after Cmax with half lives of 30-40 min. These half lives were independent of the administered doses. The mean area under the concentration-time curves (AUCs) increased from 0.398 (+/- 0.038) to 30.0 (+/- 2.7) micrograms h mL-1 as the dose increased from 10 to 800 mg. Linear relations between the doses and Cmax and AUCs were observed. The correlation coefficients for Cmax and AUC were 0.930 and 0.960, respectively. The apparent oral clearance (CL/F) and renal clearance (CLR) did not change significantly as dose increased from 10 to 800 mg. The kinetics of DP-1904 proved to be linear in the dose range studied.(ABSTRACT TRUNCATED AT 250 WORDS)

ChemInform Abstract: Synthesis of Pyrazole Derivatives as Potential Bioisosteres of Thromboxane-Synthetase Inhibitors.

A series of ω-carboalkenyl pyrazole derivatives have been synthesized as potential thromboxane-synthetase inhibitors considering the close bioisosteric relationship between the pyrazole ring and other heteroaromatic carboalkenyl compounds exhibiting inhibitory activity. (E)-7-(1-Phenylpyrazol-4-yl)hept-2-enoic acid (4b) were prepared in 28% overall yield from its minor bis-homologue, (E)-5-(1-phenylpyrazol-4-yl)pent-2-enoic acid (4a), obtained from 4-formyl-1-phenylpyrazole (6) in 17% overall yield. Compounds 4a, 4b, 7, 8 and 13 were screened for their ability to inhibit the in vitro rabbit blood platelet aggregation induced by collagen using the Born test. Among the active compounds 4a exhibited an important inhibition at 1 μM concentration.

Effects of a thromboxane-synthetase inhibitor in patients with chronic persistent coughing and no airwayhyperresponsiveness

We studied the effects of the thromboxane-synthetase inhibitor ozagrel in 22 patients with chronic persistent coughing who did not have airwayhyperresponsiveness. Treatment with ozagrel (400 mg/day for 2 weeks) reduced coughing in 12 patients. Sputum from the patients in whom ozagrel was effective had a higher percentage of lymphocytes and a lower percentage of neutrophils than did sputum from those in whom ozagrel was not effective. Furthermore, in the former group the capsaicin cough threshold increased but in the latter it did not change consistently. These data indicate that thromboxane A2 may contribute to coughing associated with lymphocytic airway inflammation.

Human whole blood assay for rapid and routine testing of non-steroidal anti-inflammatory drugs (NSAIDs) on cyclo-oxygenase-2 activity

Aim of this study was to present a simple, fast and reliable method to examine the capacity of NSAIDs to inhibiting COX-2 activity that uses rapid (stimulation takes only 5 h compared to other existing protocols) and routine testing. The assay includes elimination of COX-1-activity using ASS (a selective COX-1 inhibitor) and the thromboxane synthetase inhibitor (TXBSI), COX-2 induction via LPS and measurement of PGE(2). Using TXBSI reduces the amount of LPS and results in higher prostaglandin production. Cremophor EL-EtOH was used as vehicle instead of DMSO because within a defined concentration range, Cremophor EL-EtOH allows even very hydrophobic drugs to be solubilized and applied in vitro without cell damage. Cremophor EL-EtOH at 0.2% was optimal as at this relatively low concentration excellent drug dissolution was obtained whereas many hydrophobic substances precipitate in 0.2% DMSO. Our results demonstrate that the IC(50) values for the tested NSAIDs are in the range of published data.

UP-REGULATED THROMBOXANE PRODUCTION IN THE RAT LIVER WITH BILIARY OBSTRUCTION DOES NOT CONTRIBUTE TO PROMOTE HEPATIC INJURY

This study sought to determine whether in vivo inhibition of thromboxane A2 (TXA2) action contribute to attenuate hepatic damage after bile duct ligation (BDL). Male Wistar rats were assigned to sham operation or BDL. At the time of operation, infusion pump with saline, ozagrel natrium (TXA2 synthase inhibitor), or SQ29548 (TXA2 receptor antagonists) was implanted in the abdominal cavity. Plasma alanine aminotransferase, aspartate aminotransferase, hyaluronic acid, and total bilirubin levels were measured at 4 days after the operation. The levels of plasma TXB2, a stable metabolite of TXA2, were significantly increased after BDL. Gene expression of TXA2 synthase was also significantly upregulated in the liver. Nonetheless, either an inhibition of TXA2 synthesis by ozagrel natrium or a blockade of TXA2 receptor by SQ29548 has no effect in every measured parameter related to hepatic function. These results indicated that despite a highly increased production in the liver, TXA2 is not directly related to the hepatic injury in BDL rats.

Cyclooxygenase-dependent vasoconstricting factor(s) in remodelled rat femoral arteries

Denudation and regeneration of the vascular endothelium are important in the pathogenesis of atherosclerosis. The aim of this study is to clarify the mechanisms of functional alterations in remodelled arteries following endothelial injury. Non-mechanical endothelial injury was induced by 540-nm light irradiation of rose Bengal in femoral arteries of Wistar rats. Endothelium-dependent vasodilation was assessed by the response to acetylcholine (ACh) 1, 2, and 4 weeks after the injury. In control arteries, ACh-induced relaxation was mainly nitric oxide-dependent at all study time points. In injured arteries, this response was completely restored at 1 week, but was more dependent on KCl-sensitive endothelium-derived hyperpolarizing factor production during the first 2 weeks. Cyclooxygenase (COX) isoforms 1 and 2 were detected in the endothelium of injured arteries, and inhibition of prostanoids production with the non-specific COX inhibitor indomethacin substantially enhanced the ACh-induced vasorelaxation response in injured arteries, but did not affect control arteries. Similar effects were observed with the COX-1 inhibitor SC-560, the COX-2 inhibitor NS-398, the thromboxane (TX) A2/prostaglandin (PG) H2 receptor antagonist SQ29548 and the PGF2alpha receptor antagonist AL-8810. However, the TX synthetase inhibitor OKY-046 had no effect on ACh-induced relaxation in injured arteries. In remodelled arteries following photochemical endothelial injury, the vasoconstrictive prostanoids PGH2 and PGF2alpha, but not TXA2, contribute to changes in endothelium-dependent vascular response via COX-1- and 2-dependent pathways.

Involvement of Leukotriene Production in Release of Hepatic Lipase Activity Produced by Heparin from Rat Hepatocytes

Heparin is known to stimulate the release of hepatic lipase (HTGL) activity from hepatocytes, but the action mechanisms have not been fully confirmed. Here, we investigated the involvement of the arachidonate pathway in the heparin-stimulated release of HGTL activity from rat hepatocytes. Heparin increased phospholipase (PL) A2 activity in the hepatocytes in a time- and dose-dependent manner. The stimulatory effect of heparin on PLA2 activity was markedly decreased by incubation with protein tyrosine kinase (TK) inhibitors. It was also observed that heparin rapidly increased leukotriene (LT) B4 and LTC4/D4/E4 contents in the hepatocytes. In addition, the stimulatory release of HTGL activity by heparin was suppressed by cytosolic PLA2, 5-lipoxygenase and LTA4 hydrolase inhibitors, but not by cyclooxygenase and thromboxane (TX) synthetase inhibitors or a TXA2 receptor antagonist. These findings suggest that the heparin-stimulated release of HTGL activity from hepatocytes is partly due to an action involving increases in cytosolic PLA2 activity and LTs production with associated of TK activity.

Do prostacyclin and thromboxane play a role in endotoxic shock?

The role of prostacyclin and thromboxane during endotoxic shock is unknown. Using new radioimmunoassay techniques, we have studied the plasma levels of stable metabolites of prostacyclin (6-keto-PGF1 alpha) and thromboxane (TxB2) in a porcine model of endotoxic shock. TxB2 levels were markedly elevated but the production of prostacyclin appears to be impaired. Correction of this prostanoid imbalance by the infusion of prostacyclin or pre-treatment with a specific thromboxane synthetase inhibitor produces significant and beneficial effects on blood pressure and pre-kallikrein activation.

Bioelastic membranes for topical application of a thromboxane synthetase inhibitor for protection of skin from pressure injury: a preliminary study.

A previous study showed that topical exposure to bioelastic-thromboxane synthetase inhibitor-matrix resulted in local tissue concentrations of thromboxane synthetase inhibitor sufficient for thromboxane synthetase inhibition. The objective of this research was to use an animal model to determine if a dressing having controlled release of thromboxane synthetase inhibitor (dazmegrel) could be used to prevent tissue breakdown over pressure points, i.e., lesion at the assistive device-skin interface. The animal model studies utilized the greyhound, a dog that has thin skin, angular conformation, limited body fat and is predisposed to pressure ulcers similar to those occurring in humans. The model uses a short-limb walking cast on one pelvic limb with the severity of the dermal pressure lesions induced over the medial malleolus controlled by the amount of padding in the cast and length of time the cast is in place. The bioelastic matrix loaded with dazmegrel provided protection from shearing and pressure skin injury over the medial malleolus, as evidenced by a decrease in epidermal abrasion/ulceration as measured with planimetry. Histopathologic evaluation of the skin over the medial malleolus indicated a protective function of the bioelastic matrix as measured as lower numbers of neutrophils, lymphocytes, and decreased collagen density compared to such numbers when no bioelastic matrix was present. These studies provided evidence that bioelastic-thromboxane sythetase inhibitor- matrix helps in preventing or reducing the severity of pressure lesions, e.g., assistive device-skin interface wounds.

Down-regulation of lipoxin A 4 receptor by thromboxane A 2 signaling in RAW246.7 cells in vitro and bleomycin-induced lung fibrosis in vivo

Lipoxins (LXs) are members of eicosanoid family that can be endogenously produced during cell-to-cell interactions such as platelet–leukocyte interactions. Anti-inflammatory function of lipoxin A 4 (LXA 4) as “braking signals” is mediated by the receptor. On the other hand, thromboxane A 2 (TXA 2) produced by catalysis of cyclooxygenase and thromboxane synthetase is released during platelet aggregation as a vasoconstrictor and a pro-inflammatory factor. To investigate interaction of TXA 2 receptor (TP) and LXA 4 receptor, effects of a TP agonist and a thromboxane synthetase inhibitor on expression of LXA 4 receptor were examined in vitro and in vivo. A TP agonist, U46619 showed a down-regulation of LXA 4 receptor induced by interleukin-1β (IL-1β) in RAW246.7 cells. In bleomycin-induced lung fibrosis in mice, administration of a thromboxane synthetase inhibitor DP-1904 increased LXA 4 receptor mRNA and decreased type I collagen mRNA. In vitro experiments indicate that LXA 4 significantly prevented enhanced proliferation of NIH3T3 fibroblasts and the collagen expression by transforming growth factor-β (TGF-β). These results suggest that TXA 2-TP signaling could cause negative regulation of lipoxin A 4 receptor under the transcriptional level during inflammatory process mediated by IL-1β and TGF-β induce the expression of LXA 4 receptor. Furthermore, the down-regulation of LXA 4 receptor by TXA 2 implies a possibility that a cellular signaling by TXA 2 may have a novel and potential function as a pro-inflammatory factor to inhibit anti-inflammatory effect of LXA 4. Concomitantly, selective blockade of TXA 2-TP signaling could be suggested to lead to anti-inflammation through active role of LXA 4.

In vitro skin penetration of dazmegrel delivered with a bioelastic matrix

The penetration of dazmegrel, a selective thromboxane synthetase inhibitor, through excised human and greyhound skin was measured. A bioelastic matrix was used for topical delivery. Results demonstrated that dazmegrel readily penetrated the skin. Penetration through greyhound skin was significantly greater than penetration through human skin. Penetration through greyhound skin was not significantly different between 4, 24, and 48 h of exposure for the low and intermediate doses studied.

Protective effect of FK506 and thromboxane synthase inhibitor on ischemia-reperfusion injury in non-heart-beating donor in rat orthotopic liver transplantation.

The study investigated the possibility of pharmacologically modulating hepatic allograft function from non-heart-beating donors (NHBDs) using male Lewis rats. The donors were divided into 4 groups: Group 1 in which the vehicle was administered, Group 2 in which FK506 (tacrolimus; a powerful immunosuppressive agent) was administered, Group 3 in which OKY046 (a specific thromboxane synthetase inhibitor) was administered and Group 4 in which FK506 and OKY046 were administered. The recipients received orthotopic liver transplantation. The survival rates differed significantly between the recipients that had received liver transplantation from Groups 1 and 4. The serum liver enzyme and inflammatory cytokine concentrations of the recipients which had received liver transplantation from Groups 2, 3 and 4 were significantly lower than those of the recipients that had received liver transplantation from Group 1. Although there was no significant difference, all parameters were better in the recipients that had received transplantation from Group 4 than those that had received transplantation from Groups 2 and 3. The action mechanisms of FK506 and OKY046 are completely different. Therefore, concomitant use of FK506 and OKY046 might have additive effects on liver transplantation from NHBDs. In conclusion, we demonstrated that pretreatment of NHBDs using FK506 and OKY046 ameliorated graft viability.

Effects of simvastatin on endothelial function after chronic inhibition of nitric oxide synthase by L-NAME.

Blood pressure, plasma NO(2) and NO(3) level, heart weight index, antioxidant enzyme activity, and vascular reactivity in rat intact aortic rings were assessed to investigate the effects of 8-week treatment with the hydroxy-methyl-glutaryl coenzyme A reductase inhibitor simvastatin (1 mg/kg per day) on endothelial dysfunction induced by chronic Nomega-nitro-l-arginine methyl ester (l-NAME 70 mg/kg per day). Results were compared with those obtained in rats receiving l-NAME, simvastatin or control animals. Coadministration of simvastatin did not restore l-NAME-increased blood pressure but normalized heart weight index (P < 0.05), endothelium-dependent relaxation to acetylcholine (P < 0.001), and plasma NO(2) and NO(3) concentration (P < 0.001) without affecting relaxation to sodium nitroprusside. Endothelium-dependent relaxation in these animals was abolished by acute incubation with l-NAME, unaffected by thromboxane synthetase inhibitor and TXA(2)/PGH(2) receptor antagonist, ridogrel, and decreased by indomethacin. Simvastatin treatment also increased plasma NO(2)+NO(3) without affecting endothelial function, heart weight index, and blood pressure of control rats. The presence of superoxide dismutase (SOD) and catalase improved endothelial relaxation only in l-NAME-treated rats, but O(2)- generated by hypoxanthine and xanthine oxidase inhibited the relaxant effect in both l-NAME and simvastatin plus l-NAME-treated rats. SOD activity was increased in all groups receiving simvastatin. Long-term treatment with simvastatin restored l-NAME-induced endothelial dysfunction, probably by preventing nitric oxide decrease. Other effects of simvastatin, including release of compensating vasodilatory cyclo-oxygenase products and increased SOD activity, could also be involved.

Edaravone, a radical scavenger, may enhance or produce antiproliferative effects of fluvastatin, amlodipine, ozagrel, GF109203X and Y27632 on cultured basilar artery smooth muscle cells.

Proliferation of vascular smooth muscle cells stimulated by reactive oxygen species (ROS) may play a pivotal role in the pathogenesis of atherosclerosis. To clarify mechanisms by which ROS promote vascular atherogenesis, effects of fluvastatin, amlodipine, ozagrel (thromboxane synthetase inhibitor), GF109203X (a protein kinase C inhibitor) and Y27632 (a ROCK inhibitor) on the proliferation of guinea-pig basilar artery smooth muscle cells (GBa-SM3) in a 5% FBS culture medium were studied over 3 d in the presence or absence of a free radical scavenger, edaravone. Viability of cells at the end of incubation was measured by the 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) test. Results demonstrated that fluvastatin and amlodipine by themselves possess antiproliferative effects on the GBa-SM3 cells at 10-100 microM and 0.1-1 microM, respectively. While edaravone possessed no antiproliferative effect by itself at 100 microM, it significantly (p<0.05) augmented the antiproliferative effects of fluvastatin and amlodipine. In addition, ozagrel, GF109203X and Y27632 possessed no appreciable effects on the cell growth by themselves. However, coincubation of edaravone at 100 microM with these agents elicited significant antiproliferative effects for ozagrel, GF109203X and Y27632 at 10-100 microM, 1-10 microM and 0.1-1 microM, respectively. In conclusion, edaravone may have clinically beneficial interactions with fluvastatin, amlodipine and ozagrel regarding the prevention of vascular atherosclerosis. The interactions between edaravone and the inhibitors of protein kinase C and ROCK were suggestive of possible contributions of ROS-triggered intracellular signals associated with these enzymes to vascular atherogenesis, but further studies are required for confirmation.