Abstract: Objective To investigate the effect of N-acetylheparin(NAH)on sepsis-induced myocardial injury and its underlying molecular mechanisms. Methods C57BL/6 mice were randomly divided into to four groups: control group(Control group), LPS-induced model group(LPS group), LPS combined with N-acetylheparin treatment group(LPS+NAH group), and N-acetylheparin(NAH group)alone group. A mouse model of sepsis-induced myocardial injury was established via intraperitoneal injection of lipopolysaccharide(LPS)at a dose of 10 mg/kg. Blood samples were collected by orbital venous puncture 18 hours post-injection, followed by serum separation and heart tissue harvesting. Cardiac function was evaluated using small animal echocardiography, while the extent of myocardial injury was assessed through hematoxylin-eosin(HE)staining, the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling(TUNEL)was used to observe the apoptosis rate of cardiomyocytes. The serum levels of creatine kinase isoenzyme MB(CK-MB), cardiac troponin I(cTnI)and high-mobility group box 1(HMGB1)were quantified using enzyme-linked immunosorbent assay(ELISA). The concentrations of total glutathione peroxidase(GSH), superoxide dismutase(SOD), malondialdehyde(MDA), and tissue iron in myocardial tissue were determined using commercial assay kits. Western blotting analysis was employed to quantify the protein expression levels of high mobility group box-1(HMGB1)and glutathione peroxidase 4(GPX4)in myocardial tissue. Results Compared with the Control group, mice in the LPS group exhibited significantly reduced left ventricular ejection fraction and fractional shortening at 18 hours post-injection. Serum CK-MB and cTnI levels were markedly elevated. HE staining revealed increased inflammatory cell infiltration and structural disarray in myocardial tissue, while TUNEL staining indicated a significantly higher rate of cardiomyocyte apoptosis. Additionally, myocardial iron content and MDA levels were significantly increased, whereas GSH, SOD, and GPX4 levels were decreased. Both serum and myocardial HMGB1 expression levels were upregulated. In contrast, NAH treatment in the LPS+NAH group effectively improved left ventricular systolic function, reduced myocardial enzyme release, and ameliorated histopathological damage. Furthermore, NAH administration attenuated cardiomyocyte apoptosis, lowered myocardial iron accumulation and MDA production, and restored antioxidant enzyme activities(GSH and SOD)as well as GPX4 expression. Notably, both serum and cardiac HMGB1 levels were significantly downregulated following NAH intervention, as confirmed by ELISA and Western blotting analysis. There was no statistically significant difference between the NAH group and the Control group. Conclusion NAH alleviates lipopolysaccharide-induced myocardial injury by suppressing HMGB1 expression, upregulating GSH and GPX4 levels and total SOD activity, reducing iron and MDA content in myocardial tissues, and thereby attenuating cardiomyocyte ferroptosis.

Key words: Sepsis, Cardiomyopathy, N-acetylheparin, Ferroptosis, Lipopolysaccharide