Objective: To observe the effects of hydrogen sulfide (H2S) on structure and function of mitochondria of lung in rats with acute lung injury (ALI) induced by lipopolysaccharide (LPS).
Methods: Forty healthy male Sprague-Dawley (SD) rats were randomly divided into control group, LPS injury group, and low-, middle-, and high-dose NaHS groups, with 8 rats in each group. The rats in LPS injury group were given LPS 5 mg/kg via sublingual vein, and those in low-, middle-, and high-dose NaHS groups were challenged by LPS for 3 hours followed by intraperitoneally injection of 0.78, 1.56 and 3.12 mg/kg NaHS respectively in a volume of 2 mL/kg. The rats in control group were given 2 mL/kg normal saline via sublingual vein. The rats were sacrificed at 6 hours after model reproduction, and the lung tissues were harvested on time. The mitochondria in lung tissues were isolated with differential centrifugation. The lung mitochondria ultra structures were observed with electron microscope. The content of malondialdehyde (MDA) in mitochondria was determined with thiobarbituric acid method, and the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and adenosine triphosphatase (ATPase) were determined with xanthine oxidase method. The mitochondrial activity and swelling were determined by multiskan spectrum.
Results: It was shown by transmission electron microscope that the mitochondrial structure in the control group was normal. The mitochondria in rat lung cells was swollen with disrupted or disintegrated cristae, the osmiophilic lamellar bodies had fused or disappeared, and rough endoplasmic reticulum degranulation phenomenon was obvious in LPS injury group. The mitochondrial damage was slightly mitigated in the low-dose NaHS group, and it was significantly mitigated in the middle-dose and high-dose NaHS groups. Compared with control group, the MDA content in lung mitochondria in LPS injury group was significantly increased (nmol/mg: 26.30±1.45 vs. 11.16±1.20), and SOD, GSH-Px, and ATPase activities were significantly decreased [SOD (U/mg): 18.78±1.13 vs. 27.44±1.97, GSH-Px (U/mg): 63.91±1.99 vs. 128.15±3.47, ATPase (U/mg): 4.83±0.25 vs. 9.92±0.65]; as well as the activity of the mitochondria was significantly decreased (A value: 0.164±0.025 vs. 0.319±0.045), and the swelling of the mitochondria was significantly increased (A value: 0.182±0.012 vs. 0.273±0.023), all with significantly statistical differences (all P < 0.01). Compared with LPS injury group, the MDA contents in low-, middle-, and high-dose NaHS groups were significantly decreased (nmol/mg: 21.89±1.23, 17.63±1.56, 12.19±1.30 vs. 26.30±1.45), and the SOD, GSH-PX, and ATPase activities were significantly increased [SOD (U/mg): 20.13±0.85, 21.38±1.22, 24.05±1.56 vs. 18.78±1.13; GSH-Px (U/mg): 82.06±1.65, 101.45±2.14, 117.80±2.12 vs. 63.91±1.99; ATPase (U/mg): 5.34±0.23, 7.06±0.37, 8.78±0.44 vs. 4.83±0.25]; as well as the activity of the mitochondria was markedly increased (A value: 0.194±0.018, 0.230±0.032, 0.297±0.038 vs. 0.164±0.025), and the swelling of mitochondria was markedly decreased (A value: 0.195±0.008, 0.219±0.017, 0.249±0.018 vs. 0.182±0.012), all with significantly statistical differences (all P < 0.05). Moreover, the protective effect of NaHS showed a dose-dependent manner.
Conclusions: It could be concluded that LPS induce mitochondrial structural damage and functional impairment in rats with ALI induced by LPS, and H2S have a beneficial effect against ALI induced by LPS with decreasing the mitochondrial lipid peroxidation level and protecting the cell structure and function, and the effect is correlated with the dosage.