^99mTc-HSA is a valuable tracer in monitoring acute lung injury induced by lipopolysaccharide in rats

Objectives To evaluate the effectiveness of Tc-99m labeled human serum albumin (^99mTc-HSA) in monitoring acute lung injury (ALI) induced by lipopolysaccharide (LPS) in rats.

Methods Twenty adult male Wister rats were given ^99mTc-HSA 3.7MBq intravenously, and were randomly divided into four groups at 30 minutes post-injection of Tc-99m-HSA. The control group was injected with 0.9% saline 0.5 ml intravenously, while the LPS group was injected with LPS 8 mg/kg (0.5 ml). Thirty minutes after the LPS injection, the ketamine group was administered intraperitoneally with ketamine 4mg/kg, while the aminoguanidine group was administered with aminoguanidine 20mg/kg. All of the rats were killed by blood letting at 3 hours post-injection of Tc-99m-HSA. Bronchoalveolar lavage were performed with 20 mL phosptat buffe. Radioactivity in the bronchoalveolar lavage fluid (BALF) and serum was measured by a well-type γ counter. The pulmonary permeability index (PPI) was expressed as the ratio of radioactivity in BALF/ radioactivity in 1 mL serum. The lung weight ratio of wet and dry (W/D) was also calculated in control and LPS group.

Results The values of PPI (*10^-3) and W/D in control and LPS group were 6.61±0.18 and 4.19±0.11, 95.58±11.32 and 5.38±0.24, respectively. The values of PPI (*10^-3) in ketamine and aminoguanidine group were 36.80±7.22 and 33.54±6.22, respectively. The PPI in LPS group was much higher than that in the other three groups (P<0.05). Although the W/D in LPS group was also higher than that in control one (P<0.05), the increase of PPI was more prominent.

Conclusions ^99mTc-HSA is an effective tracer in monitoring ALI induced by LPS in rats. Ketamine and aminoguanidine are effective pharmaceuticals in alleviating ALI.