Simple hemorrhage induces tissue factor mRNA in the liver

Biochemical properties and comparative pharmacology of a coagulant from Deinagkistrodon acutus snake venom

A number of snake venom thrombin-like enzymes (TLEs) have already been characterized. Some TLEs play significant roles in vessel injury hemostasis. A novel TLE (Agacutase) was purified from Deinagkistrodon acutus snake venom by the means of Sephadex G-75, DEAE-Sepharose FF, and Sephadex G-25 column chromatography. Structural analysis indicated that Agacutase is a single-chain glycoprotein with a molecular mass of 31,084 Da, isoelectric point of 4.38, optimal activity at 37 °C and pH 6.6, sugar content of 7.6%. Its N-terminal 44 amino acid sequence was determined to be VIGGNECDTNEHRFLAAFFTSRPWIFQCAGTLIHEEWVLAAAHC, showing maximum identity of 80% with that of Dav-X protease. The Agacutase-induced clotting activity was not influenced by heparin, hirudin, or Dextran 40, but activated by Ca(2+) and inhibited by PMSF or lactose, which suggests that Agacutase is a serine protease and the coagulation activity is independent of Thrombin. Agacutase with arginine esterase activity specifically cleaves the α-chain of fibrinogen. Agacutase iv (0.03-0.12 U/kg) shortened 16-68% of the rabbit blood clotting time. No significant influence was indicated on platelet, Factor II and XIII, or fibrinolytic system. It converts fibrinogen into the soluble fibrin that accelerates hemostasis at wound. Pharmacological comparison showed the hemostatic effect of Agacutase lasted 24h while Reptilase did 8h. Its maximum tolerated, abnormal toxicity, allergic, and hemorrhagin doses were 80 U/kg, 1 U, 2 U, and 50 U, respectively, whereas those of Reptilase or Agacutin were 35 U/kg, 0.25 U, 0.25 U, and 0.2 U, respectively. The results indicated that Agacutase may be a predominant coagulant.

Adrenalectomy enhances response of tumour necrosis factor-alpha (TNF-alpha) to haemorrhage in the conscious rat

Several factors have been implicated in TNF-alpha induction after haemorrhage, but the precise mechanism is unknown. To assess a possible role of adrenal glands on TNF-alpha induction after haemorrhage, adrenalectomized (ADX) and sham-adrenalectomized (Sham) rats were subjected to 20 ml/kg haemorrhage (approximately 30% of the total blood volume) over 5 min in the conscious state, and changes in serum TNF and hepatic TNF-alpha mRNA were analysed by cytotoxicity against L929 cells and by semiquantitative reverse transcription-polymerase chain reaction, respectively. Changes in plasma corticosterone (CS) and mean arterial blood pressure (MABP) were also detected. Plasma CS levels showed a rapid increase after haemorrhage in Sham rats, whereas there was no response in ADX rats. Responses of MABP were comparable in the two groups. Both serum TNF and hepatic TNF-alpha mRNA showed rapid increases after haemorrhage in the Sham group, and these increases were significantly augmented in the ADX group. Pretreatment with CS (100 microg/h) negated these augmentations in ADX rats. These results show that adrenalectomy enhances the response of TNF-alpha to 20 ml/kg haemorrhage in the conscious rat, and suggest that endogenous glucocorticoids may play an inhibitory role in the induction of TNF-alpha after haemorrhage.

Responses of hepatic TNF-alpha mRNA to repeated hemorrhage in the conscious rat

Trauma victims may suffer from repeated hemorrhage, but responses of cytokines to it have not been described. To study this question, we first detected the time course of changes in serum tumor necrosis factor (TNF) activity and hepatic TNF-alpha mRNA by cytotoxicity against L929 cells and by reverse transcription (RT) and polymerase chain reaction (PCR), respectively, after different sizes of hemorrhage (10-20 ml/kg) with chronically cannulated rats. Then we examined the changes in TNF-alpha mRNA when two sequential 10 ml/kg hemorrhages were performed. TNF activity showed no significant increases after either size of hemorrhage. At mRNA level, both 15 ml/kg and 20 ml/kg hemorrhages induced significant increases after hemorrhage, whereas a 10 ml/kg hemorrhage did not. When the 10 ml/kg hemorrhage was repeated 24 h later, however, TNF-alpha mRNA showed a significant increase. There were no significant differences in blood pressure and heart rate after single and repeated 10 ml/kg hemorrhage. This potentiation persisted for >/=48 h. These results show that responses of hepatic TNF-alpha mRNA are augmented when moderate hemorrhage is repeated.

Bactericidal/permeability-increasing protein ameliorates hypercoagulability after hemorrhagic shock

We recently showed that both plasminogen activator inhibitor-1 (PAI-1) and tissue factor (TF) are induced after a massive hemorrhage. In this study, we determined if bactericidal/permeability-increasing protein (BPI) has any effects on the induction of these factors after hemorrhagic shock. Three days after cannulation, rats were bled and maintained at a mean blood pressure of 40 mmHg for 60 min, and then were resuscitated with the shed blood and an equal volume of saline over 60 min. Rats in the BPI group were given at 6 mg/kg of rBPI21 (XOMA, Berkeley, CA; a 3-mg/kg dose at the beginning of hemorrhage followed by two doses of 1.5 mg/kg at the end of shock and at the end of resuscitation). The control group was treated similarly to the BPI group, but received control protein in the same dose as rBPI21. Plasma endotoxin concentration, whole blood clotting time (WBCT) and plasma PAI activity were measured at times 0, 2, 4, 6, and 8 h. The time-course changes in mRNA of TF, PAI-1, tumor necrosis factor alpha (TNF alpha), interleukin-1 beta (IL-1 beta), and interleukin-6 (IL-6) were also detected in the liver by reverse transcription and polymerase chain reaction. The plasma endotoxin levels increased after hemorrhagic shock and showed a peak at 2 h in the control group. These increases were significantly neutralized by rBPI21 treatment at 2 h in the BPI group. WBCT decreased and PAI activity increased rapidly after hemorrhagic shock in the control group. These changes were significantly smaller in the BPI group at 6 and 8 h. The increases in mRNA of TF, PAI-1, TNF alpha, and IL-6 were also attenuated by rBPI21 treatment. These results show that BPI ameliorates hypercoagulability after hemorrhagic shock and suggest that endotoxin plays a role in the pathogenesis of thrombogenic responses after hemorrhagic shock.