Effects of different doses of ulinastatin on severe thermal injury-induced myocardial damage in rats

Objective To investigate the effects of different doses of ulinastatin on severe thermal injuryinduced myocardial damage in rats. Methods One hundred and eighty female SD rats weighing 180-220 g were usedin this study. Thirty percent of the total body surface (TBS) was shaved chemically with 20% sodium sulphate and then exposed to 92 ℃ water for 18 s. The animals with third degree thermal injury involving 30% of the TBS were randomly divided into 3 groups (n = 60 each): group Ⅰ thermal injury (group TI); group Ⅱ and Ⅲ received intraperitoneal ulinastatin 40 000 and 80 000 U/kg respectively immediately after thermal injury (group U1 , U2). The TI group received equal volume of normal saline IP instead of ulinastatin. Blood samples were taken from abdominal aorta before (baseline) and at 1, 3, 6, 12 h after thermal injury for determination of serum concentrations of cTnI, IL-1β, IL-6, IL-10 and TNF-α (10 samples at each time points). Ten animals were sacrificed at each time point after blood sampling. The myocardial specimens were obtained for microscopic examination and measurement of MDA content and SOD activity. Results Compared with group TI, the serum concentrations of cTnI, IL-1β, IL-6 and TNF-α and MDA content in myocardium were significantly decreased and the myocardial SOD activity was significantly increased in group U1 , while in group U2 the senum concentrations of cTnI, IL-Iβ, IL-6 and TNF-α and myocardial MDA content were significantly increased and the myocardial SOD activity was significantly decreased. There was no siginificant difference in the serum concentrations of IL-10 among the three groups. Microscopic examination showed that myocardial damage was accentuated in group U2 as compared with group U1. Conclusion Ulinastatin 40 000 U/kg can ameliorate severe thermal injury-induced myocardial injury through inhibition of inflammatory response and lipid peroxidation response, whereas ulinastatin 80 000 U/kg accentuates myocardial damage. Key words: Trypsin inhibitors;  Burns;  Myocardium