Therapeutic efficiency of nitric oxide synthase inhibitor on traumatic shock in rats

Objective:To evaluate the effects of aminpguandine(AG) used as a selective inhibitor of the inducible form of nitric oxide synthase(iNOS) and NnitroLarginine methyl ester(LNAME) used as a nonselective inhibitor of nitric oxide synthase(NOS) on traumatic shock.Methods:Thirty SD(SpragueDawley) rats were used to create a animal model of traumatic shock.Both shaft of femurs were crashed and bled to mean arterial pressure of 35-45 mm Hg(1 mm Hg=0.133 kPa) via femoral artery.Hypotention was maintained 30 minutes,the shed blood was then returned,followed by an infusion with Ringer's solutions. Animals were randomly divided into three groups:traumatic shock group(n=10),AG group(AG 8 mg/kg was infused at resuscitation,n=10),LNAME group(LNAME 8 mg/kg was infused at resuscitation, n=10).Plasma levels of nitric oxide(NO) were determined before and after shock,immediately after resuscitation and 0.5,2 and 4 hours after resuscitation.The 24 hours survival rates were recorded.Lung,liver and kidney, intestine tissues were obtained 24 hours after shock for microscopic examination.Results:The plasma level of NO markerly increased after shock.The plasma level of NO markerly decreased and less tissue damages with highly survival rates in AG group.Lower plasma level of NO and survival rates and highly tissue damages were seen in LNAME group.Conclusion:NO plays an important role in development of pathologically traumatic shock.AG is beneficial of treatment in traumatic shock,but LNAME can only decrease the plasma level of NO and can not improve the outcome of shock.