Background: Shen-Fu injection (SFI) can attenuate ischemia-reperfusion injury, protect cardiac function, and improve microcirculation during cardiopulmonary resuscitation.We hypothesized that SFI may also have an influence on myocardial metabolism during ventricular fibrillation (VF).In this study, we used SFI pretreatment prior to VF to discuss the changes of myocardial metabolism and catecholamine (CA) levels during untreated VF, trying to provide new evidence to the protection of SFI to myocardium.Methods: Twenty-four pigs were divided into three groups: Saline group (SA group), SFI group, and SHAM operation group (SHAM group).Thirty minutes prior to the induction of VF, the SFI group received 0.24 mg/ml SFI through an intravenous injection;the SA group received an equal amount of sodium chloride solution.The interstitial fluid from the left ventricle (LV) wall was collected through the microdialysis tubes during VF.Adenosine diphosphate (ADP), adenosine triphosphate (ATP), and Na+-K+-ATPase and Ca2+-ATPase enzyme activities were measured after untreated VF.Peak-to-trough VF amplitude and median frequency were analyzed for each of these 5-s intervals.Results: The levels of glucose and glutamate were lower after VF in both the SA and SFI groups, compared with baseline, and the levels in the SFI group were higher than those in the SA group.Compared with baseline, the levels of lactate and the lactate/pyruvate ratio increased after VF in both SA and SFI groups, and the levels in the SFI group were lower than those in the SA group.In both the SA and SFI groups, the levels of dopamine, norepinephrine, and epinephrine increased significantly.There were no statistical differences between the two groups.The content ofATP, ADP, and phosphocreatine in the SFI group was higher than those in the SA group.The activity of LV Na+-K+-ATPase was significantly higher in the SFI group than in the SA group.Amplitude mean spectrum area (AMSA) was significantly lower in the SA and SFI groups at 8-and 12-min compared with 4-min.The AMSA in the SFI group was higher than that in the SA group at each time point during untreated VF.Conclusions: SFI pretreatment can improve myocardial metabolism and reduce energy exhaustion during VF, and it does not aggravate the excessive secretion of endogenous CAs.