Toxicity and Side Effects of Inhaling Nitric Oxide on the Liver of Rats

Objective To evaluate the toxicity and side effects of exogenous nitric oxide(NO) on the liver of normal rats.Method 72 rats were divided into three groups randomly.Group 1(n=24) inhaled oxygen only(FiO 2=0.40);Group 2(n=24) inhaled low content of NO(40ppm);Group 3(n=24) inhaled high content of NO(80ppm).The last two groups were also given oxygen inhalation(FiO 2=0.40).After 2,8,12 and 24 hours of the experiment,the specimen was fetched and examined.In addition,other 6 rats served as control group.The data were analyzed with ANOVA for multiple mean comparison.Results There was no significant difference in water content of the liver tissue among three groups( P 0.05).The concentration of NO 2 in Group 3 was significantly higher than that in Group 1 and 2( P 0.05 and P 0.01).The level of glutamic pyruvic transaminase enzyme in Group 3 was higher than that in Group 1( P 0.01),Group 2 and control group( P 0.05).Total bilirubin in Group 2 was lower than that in Gruop 1 and 3( P 0.01).The concentration of methemoglobin in Grouop 3 was higher than that in Group 1 and 2( P 0.05, P 0.05).The histological and morphological changes of liver in Group 2 were lighter than those in Group 1 and 3.Conclusions No significant toxicity and side effect of nitric oxide are found on normal rats' liver tissue inhaling 40ppm NO,but 80ppm NO inhalation is harmful to liver of rats.