Objective To investigate the protective effects of butyrate on sepsis-related myocardial dys-function.Methods Thirty healthy 8-week-old male Sprague-Dawley rats were randomly divided into three groups:sham operation group(SH,n=10),sepsis group(CL,n=10),and butyrate group(BU,n=10).The CL and BU groups underwent cecal ligation and puncture(CLP)to establish sepsis models,while the SH group received the same surgical procedure without cecal ligation or puncture.Within 30 minutes post-opera-tion,the SH and CL groups received 5 mL normal saline via gavage,whereas the BU group was administered 5 mL sodium butyrate solution(500 mg/kg)in normal saline.Cardiac output(CO)and ejection fraction(EF)were compared among the three groups.Myocardial histopathological injury was assessed by HE staining,and mitochondrial ultrastructural damage was observed by electron microscopy.Serum levels of brain natriuretic peptide(BNP),cardiac troponin Ⅰ(cTnⅠ),and butyrate were compared among groups.Western blot analysis was performed to detect and compare the expression levels of long-chain acyl-CoA synthetase 4(ACSL4)and glutathione peroxidase 4(GPX4)in myocardial tissues.Results After intervention,the BNP and cTnⅠ levels in the CL group were higher than those in the SH group,while CO and EF were lower than those in the SH group(P＜0.05).The BNP and cTnⅠ levels in the BU group were lower than those in the CL group,whereas CO and EF levels were higher than those in the CL group(P＜0.05).HE staining of myocardial tissues re-vealed more severe inflammatory cell infiltration and myocardial cell edema in the CL group compared with the SH group,while the BU group showed reduced inflammatory cell infiltration.Mitochondrial membrane in-tegrity was impaired in the CL group manifested by unclear cristae,swelling,vacuolar degeneration and rup-ture,whereas mitochondrial damage was attenuated in the BU group.Serum butyrate levels were measured as(61.7±21.6)μg/mL,(95.3±16.6)μg/mL and(302.2±49.7)μg/mL in the CL,SH and BU groups respec-tively(P＜0.05).The ACSL4 expression in the CL group was higher than that in the SH group,while GPX4 protein expression was lower than that in the SH group(P＜0.05).The BU group exhibited lower ACSL4 expression and higher GPX4 protein expression compared with the CL group(P＜0.05).Conclusion Buty-rate can ameliorate myocardial injury in septic rats,and its protective effect may be associated with the inhibi-tion of myocardial ferroptosis.