Brain TXA(2)and PGI(2)levels related to diffuse brain injury with secondary insults

Secondary insults such as hypotension and hypoxia with head injury are associated with increased mortality and morbidity in comparison with head injury alone. In the present study the changes of brain thromboxane A(2)(TXA(2)) and prostacyclin (PGI(2)) levels in a Marmarou's rodent model of diffuse brain injury with hypotension and hypoxia were observed and the effect of diaspirin cross linked haemoglobin solution (DCLHb) were also investigated. Thirty-two male Sprague-Dawley (SD) rats were randomized into four groups: sham; head injury alone; head injury with secondary insults; and injury with insults followed by DCLHb administration. The results showed that there were no changes in TXB(2)and 6-keto-PFG(1a)(metabolites of TXA(2)and PGI(2)) levels in the injury alone group, while TXB(2)levels in the secondary insults group were elevated significantly; both TXB(2)and 6-keto-PGF(1a)levels in the injury with insults followed by DCLHb administration group were augmented significantly in comparison with the corresponding value of sham at 4 postimpact. The only increase in TXA(2)levels in the secondary insults rats suggests that an imbalance in TXA(2)-PGI(2)production contributes to the traumatic secondary processes, which include ischaemia and oedema. It is hypothesized that DCLHb may exert its protective properties through increasing PGI(2)production in injured brain by improving blood supply to injured blood vessels. Copyright 1999 Harcourt Publishers Ltd.