[Effect of methylene blue on traumatic shock in rabbits].

Objective: To observe the effect of methylene blue (MB) on the changes in plasma nitric oxide (NO), tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and visceral pathologic changes in rabbits with traumatic shock.
Methods: Eighteen rabbits were randomly assigned into 3 groups (n=6): sham operation group, traumatic shock with normal saline (NS) resuscitation group (NS group), and traumatic shock with MB resuscitation group (MB group). In NS group and MB group, hemodynamics was monitored, and plasma contents of NO, TNF-alpha and IL-6 were determined before shock, after shock, after resuscitation, and 0.5, 2 and 4 hours after resuscitation. In sham operation control group, hemodynamics monitoring and plasma contents of NO, TNF-alpha and IL-6 were also determined. Tissue samples of the liver and intestine were obtained after experiments for microscopic examination.
Results: Compared with NS group, hemodynamics was stable in MB group. The levels of plasma NO in rabbits after traumatic shock were much higher than those of before shock. In NS group, the levels of plasma NO were progressively increased after resuscitation, reaching peak level at 0.5 hour after resuscitation, then decreased thereafter but still remaining higher than those of before shock. But in MB group, the levels of plasma NO after resuscitation were obviously decreased. In sham operation group, the levels of plasma NO showed no significant changes during the whole course. The levels of plasma TNF-alpha and IL-6 in rabbits after traumatic shock were much higher than those of before shock. But after intravenous administration of MB, the levels of plasma TNF-alpha and IL-6 after resuscitation showed no significant difference compared with the baseline levels. In sham operation group, the levels of plasma TNF-alpha and IL-6 showed no significant changes during the entire course. In NS group, the organs showed prominent pathologic changes. But in MB group, less pathologic changes in the organs were milder, and in sham operation group, there was no obvious pathologic changes in the organs.
Conclusion: NO, TNF-alpha and IL-6 play important roles in the pathologic process of traumatic shock and the administration of MB after resuscitation can decrease the levels of plasma NO, TNF-alpha and IL-6, improve hemodynamics in traumatic shock, and protect the important organs.