3-5-dimethyl-2-(3-pyridyl)thiazolidin-4-one and Disease-Models--Animal

Recently, we demonstrated that neutrophils express tissue factor (TF) in a model of acute obstructive cholangitis (AOC). However, the regulation of TF expression was not clear. In this study, we clarified the role of platelet-activating factor (PAF) in TF expression in neutrophils.. In a model of AOC, intravenous PAF antagonist, (SM-12502, 200 mg/kg) was administered 5 min before sepsis was induced. Normal saline was given as a control. Coagulation parameters and TF activity were monitored for 6 h. Thereafter, the liver was harvested for histological examination.. The percentage of neutrophils which stained positive for TF was significantly reduced by SM-12502 (74.9 +/- 19.3% vs 96.3 +/- 2.8%) (P < 0.01). The number of leukocytes infiltrating the liver was also significantly reduced. Coagulation abnormalities, TF activity, and focal necrosis of the hepatocytes were reduced by SM-12502.. SM-12502 inhibits TF expression in neutrophils which have infiltrated the liver sinusoids, reducing the subsequent infiltration of leukocytes. These results suggest that PAF plays an important role in the expression of TF in neutrophils in vivo.

Topics: Animals; Aspartate Aminotransferases; Blood Coagulation; Cholangitis; Disease Models, Animal; Leukocytes; Liver; Male; Neutrophils; Platelet Activating Factor; Rabbits; Thiazoles; Thiazolidines; Thromboplastin

Adult respiratory distress syndrome and disseminated intravascular coagulation are important pathologic conditions affecting the outcome of patients with sepsis. To elucidate the possible therapeutic efficacy of SM-12502, a novel platelet activating factor antagonist, on acute lung injury and disseminated intravascular coagulation in sepsis, we investigated the effect of SM-12502 on an endotoxin (ET)-induced septic model in rats. SM-12502 prevented ET-induced increases in pulmonary vascular permeability and ET-induced histologic changes, such as leukocyte infiltration and pulmonary interstitial edema, 6 h following the administration of ET (5 mg/kg). SM-12502 also inhibited the decrease in fibrinogen and the increase in fibrin and fibrinogen degradation products observed following ET administration. SM-12502 prevented increases in the serum concentration of tumor necrosis factor (TNF) 90 min following ET administration in vivo, and significantly inhibited the production of TNF-alpha by ET-stimulated monocytes in vitro. These findings suggest that SM-12502 attenuates the actions of endotoxin by the inhibition of TNF production.

Topics: Animals; Blood Coagulation; Disease Models, Animal; Disseminated Intravascular Coagulation; Endotoxins; Female; Humans; Infant, Newborn; Platelet Activating Factor; Pulmonary Artery; Rats; Rats, Wistar; Respiratory Distress Syndrome, Newborn; Thiazoles; Thiazolidines

The effect of SM-10661, a selective antagonist of platelet-activating factor (PAF), on passive anaphylactic bronchoconstriction was examined in guinea pigs. A challenge of ovalbumin to passively sensitized guinea pigs induced bronchoconstriction, which peaked at 4 min. When SM-10661 was administered intravenously 2 min before ovalbumin challenge, bronchoconstriction was inhibited dose-dependently with an ID50 of 68 mg/kg. In guinea pigs pretreated with 15 micrograms/kg mepyramine which is a suboptimal dose, antigen-induced bronchoconstriction peaked at 4-6 min, but was inhibited by SM-10661 with an ID50 of 21 mg/kg. When guinea pigs were pretreated intravenously with 2.5 mg/kg mepyramine, 1 mg/kg indomethacin and 0.01 mg/kg propranolol, the antigen-induced bronchoconstriction peaked at 6 min. SM-10661 inhibited the response with an ID50 of 45 mg/kg. Histamine- and leukotriene D4-induced bronchoconstrictions were unaffected by up to 100 mg/kg SM-10661. Ovalbumin challenge of minced lungs from passively sensitized guinea pigs triggered the release of leukotrienes and histamine. SM-10661 had no effect on the antigen-induced release of peptide leukotrienes or histamine up to 10(-4) M. These results indicate that SM-10661 may be a useful tool to investigate the role of PAF in antigen-induced anaphylactic bronchoconstriction.

Topics: Anaphylaxis; Animals; Asthma; Bronchoconstriction; Disease Models, Animal; Dose-Response Relationship, Drug; Guinea Pigs; Indomethacin; Male; Ovalbumin; Platelet Activating Factor; Propranolol; Pyrilamine; SRS-A; Thiazoles; Thiazolidines

The effect of a selective platelet-activating factor (PAF) receptor antagonist, SM-10661, on antigen-induced dual asthmatic response and leukocyte infiltration into the airways of actively sensitized conscious guinea pigs was investigated. The animals were pretreated with mepyramine maleate (10 mg/kg i.p.) and then challenged with ovalbumin. The inhalation of ovalbumin caused an immediate decline in specific airway conductance (sGaw) which peaked at 5 min after the challenge. sGaw gradually returned to the baseline 6 hr after the challenge. After the early asthmatic response (EAR), a second phase change, a late asthmatic response (LAR) in sGaw peaking at 17-20 hr was observed. When 1% w/v disodium cromoglycate was inhaled for 2 min on two occasions, EAR was not affected, but LAR was significantly inhibited. Oral administration of 50 mg/kg fenoterol (30 min before challenge) significantly inhibited EAR, but had no significant effect on LAR. SM-10661 administered orally 1 hr before the challenge inhibited EAR dose-dependently (50% inhibitory dose (ID50); 59 mg/kg, but was even more effective against the LAR (ID50); 13-16 mg/kg). When 30 mg/kg of SM-10661 was administered orally 6 hr after ovalbumin challenge, LAR was completely inhibited. The number of total cells, macrophages and eosinophils in bronchoalveolar lavage fluids rose significantly 17 hr after antigen challenge compared to that observed after saline challenge. The number of neutrophils and lymphocytes also increased in response to the ovalbumin challenge, but not significantly. SM-10661 (30 mg/kg) administered orally 1 hr before the challenge significantly inhibited the increase in total cells, macrophages and eosinophils.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Antigens; Asthma; Cromolyn Sodium; Disease Models, Animal; Fenoterol; Guinea Pigs; Leukocytes; Lung; Male; Ovalbumin; Platelet Activating Factor; Respiratory Function Tests; Respiratory System; Thiazoles; Thiazolidines