Objective:To explore the effect of necroptosis inhibitor necrosulfonamide (NSA) on traumatic brain injury (TBI) mouse model and BV2 cell pyroptosis model and their mechanisms.Methods:(1) In vivo experiments: 50 mice were randomly divided into sham-operated group, TBI group, TBI+1 mg/kg NSA group, TBI+5 mg/kg NSA group, and TBI+10 mg/kg NSA group, with 10 mice in each group. TBI model was established using a modified Feeney's weight-drop method; 4 h after modeling, 90% corn oil, 1 mg/kg NSA, 5 mg/kg NSA, or 10 mg/kg NSA was administered into the mice, respectively. Mice in the sham-operated group only had circular bone window opened without being subjected to impact. At 48 hours after modeling, neurological function was evaluated by modified neurological function score (mNSS), serum lactate dehydrogenase (LDH) content was detected by LDH detection kit, contents of interleukin (IL)-18, IL-1β and tumor necrosis factor-α (TNF-α) in the brain tissues were detected by enzyme-linked immunosorbent assay (ELISA), and expressions and localizations of ionized calcium binding adaptor molecule 1 (IBA-1), cysteinyl aspartate specific proteinase-1 (Caspase-1) p20 and gasdermin D (GSDMD) in the injured parietal cortex were detected by double immunofluorescent staining. (2) In vitro experiments: BV2 cells were divided into control group, lipopolysaccharide (LPS)+adenosine triphosphate (ATP)+dimethyl sulfoxide (DMSO) group, LPS+ATP+5 μmol/L NSA group, LPS+ATP+10 μmol/L NSA group, and LPS+ATP+15 μmol/L NSA group. Cells in the latter 4 groups were induced by LPS+ATP to establish BV2 cell pyroptosis model, and incubated with 2 μL DMSO, 5 μmol/L NSA, 10 μmol/L NSA, and 15 μmol/L NSA for 1 hour, respectively; cells in the control group were cultured conventionally. Contents of LDH, IL-1β, IL-18, and TNF-α in the cell culture supernatant were detected by ELISA; pyroptosis was detected by calcein acetoxymethyl ester (CAM)/propidium iodide (PI) double staining; protein expressions of nucleotide binding domain-like receptor protein 3 (NLRP3), Caspase-1 p20, GSDMD, and N-terminal fragment of GSDMD (GSDMD-N) were detected by Western blotting. Results:(1) Compared with the TBI group, the TBI+1 mg/kg NSA group, TBI+5 mg/kg NSA group and TBI+10 mg/kg NSA group had decreased mNSS score and serum LDH content, decreased IL-1β and IL-18 contents in the brain tissues and number of Caspase-1 p20 + cells in the injured parietal cortex, successively, with significant differences ( P<0.05). Compared with the TBI group ([287.80±12.26] cells/mm 2), the TBI+1 mg/kg NSA group, TBI+5 mg/kg NSA group, and TBI+10 mg/kg NSA group had decreased number of Iba-1 +GSDMD + cells in the injured parietal cortex ([213.70±11.87] cells/mm 2, [205.30±9.15] cells/mm 2, [131.70±13.69] cells/mm 2),successively, with significant differences ( P<0.05). Compared with the TBI group, the TBI+5 mg/kg NSA group and TBI+10 mg/kg NSA group had significantly decreased number of Iba-1 + cells in the injured parietal cortex, and the TBI+10 mg/kg NSA group had significantly decreased TNF-α content in the brain tissues and number of GSDMD + cells in the injured parietal cortex ( P<0.05). Compared with the TBI group ([247.20±9.88] cells/mm 2), the TBI+10 mg/kg NSA group had significantly decreased number of Iba-1 +Caspase-1 p20 + cells in the injured parietal cortex ([181.70±9.37] cells/mm 2, P<0.05). (2) Compared with the LPS+ATP+DMSO group, the LPS+ATP+5 μmol/L NSA group, LPS+ATP+10 μmol/L NSA group, and LPS+ATP+15 μmol/L NSA group had decreased IL-18 content in the supernatant, successively, with significant differences ( P<0.05); and compared with the LPS+ATP+DMSO group, the LPS+ATP+10 μmol/L NSA group and LPS+ATP+15 μmol/L NSA group had significantly decreased contents of LDH, IL-1β, and TNF-α in the supernatant and ratio of PI +/CAM + cell counts ( P<0.05). Compared with the LPS+ATP+DMSO group (2.62±0.50), the LPS+ATP+10 μmol/L NSA group and LPS+ATP+15 μmol/L NSA group had significantly decreased Caspase-1 p20 protein expression (1.36±0.14, 1.32±0.07, P<0.05). Compared with the LPS+ATP+DMSO group (5.00±1.67), the LPS+ATP+5 μmol/L NSA group and LPS+ATP+15 μmol/L NSA group had significantly decreased GSDMD protein expression (1.42±0.26, 1.68±0.32, P<0.05). Compared with the LPS+ATP+DMSO group (2.28±0.24), the LPS+ATP+15 μmol/L NSA group had significantly decreased GSDMD-N protein expression (1.23±0.08, P<0.05). Conclusion:NSA can inhibit microglial pyroptosis after TBI by inhibiting the Caspase-1 p20/GSDMD pathway, thereby playing a neuroprotective role.

OBJECTIVE To study the mechanism of Wenshen Tongdu Recipe in promoting the recovery of motor function in rats with spinal cord injury.METHODS A total of 144 SD rats were randomly divided into sham operation group,model group,predni-sone group,low-dose Wenshen Tongdu Recipe group,medium-dose Wenshen Tongdu Recipe group,high-dose Wenshen Tongdu Recipe group,3BDO group,and 3BDO+Wenshen Tongdu Recipe group(medium dose).The rat spinal cord injury model was estab-lished by modified Allen's method.Intervention began 1 day after modeling,and the drug was administered continuously for 14 days.During the drug administration period,the motor function of the rats in each group was evaluated by Basso-Beattie-Bresnahan(BBB)score and inclined plane test.On the 3rd,7th and 14th days after modeling,the pathological changes of the spinal cord tissues of the rats in each group were observed by HE staining;the expression levels of inflammatory factors IL-1β,IL-6,IL-4 and IL-10 in the serum of the rats in each group were detected by ELISA;the expression of Beclin 1,LC3B and p62 proteins was detected by immu-nohistochemistry;the expression of CD16 and CD206 proteins was detected by immunofluorescence staining;the expression of autoph-agy-related molecules(Beclin 1,LC3B)and Akt/mTOR pathway-related proteins in the spinal cord tissues was detected by Western blot.RESULTS Compared with the model group,the BBB score and angle of the inclined board test of rats in the medium-dose Wenshen Tongdu Recipe group were increased,and the disordered arrangement of spinal cord tissue,spinal cord vacuoles and inflam-matory infiltration were significantly improved,especially on the 14th day.Compared with the sham operation group,the expression levels of serum IL-1β and IL-6 in the model group increased(P<0.01),and the expression levels of IL-4 and IL-10 decreased(P<0.05,P<0.01);compared with the model group,the levels of IL-1β and IL-6 in the Wenshen Tongdu Recipe group were signifi-cantly decreased(P<0.01),and the levels of IL-4 and IL-10 were significantly increased(P<0.05,P<0.01);compared with the Wenshen Tongdu Recipe group,the serum IL-1β and IL-6 concentrations of mice in the 3BDO group increased(P<0.01),and the level of IL-10 decreased(P<0.05).Compared with the sham operation group,the M1/M2 ratio,P62 protein expression,p-Akt/Akt and p-mTOR/mTOR ratios in the spinal cord tissue of the rats in the model group were significantly increased(P<0.05,P<0.01),and the relative protein expression of Beclin1 was decreased(P<0.01);compared with the model group,the M1/M2 ratio,p-Akt/Akt and p-p70S6K/p70S6K ratios in the Wenshen Tongdu Recipe group were significantly decreased(P<0.01).Compared with the model group,the Beclin1 protein level in the 3BDO group was decreased,and the p-Akt/Akt and p-mTOR/mTOR ratios were increased(P<0.05,P<0.01).Compared with the Wenshen Tongdu Recipe group,the M1/M2 ratio in the 3BDO group and the 3BDO+Wen-shen Tongdu Recipe group increased(P<0.01),the positive rates of Beclin1 and LC3B proteins in the 3BDO group decreased signifi-cantly(P<0.01),and the p-p70S6K/p70S6K ratio in the 3BDO+Wenshen Tongdu Recipe group increased significantly(P<0.01).CONCLUSION Wenshen Tongdu Recipe may regulate microglial polarization through Akt/mTOR signaling pathway to acti-vate autophagy,promote the secretion of anti-inflammatory factors,reduce the release of pro-inflammatory factors,alleviate neuroin-flammatory response,and thus promote spinal cord injury repair.

OBJECTIVES: We propose a multi-scale jaw cyst segmentation model, AConvLSTM U-Net, which is based on bidirectional dense connections and attention mechanisms to achieve accurate automatic segmentation of mandibular cyst images. METHODS: A dataset consisting of 2592 jaw cyst images was used. AConvLSTM U-Net designs a MBC on the encoding path to enhance feature extraction capabilities. A DPD was used to connect the encoder and decoder, and a bidirectional ConvLSTM was introduced in the jump connection to obtain rich semantic information. A decoding block based on scSE was then used on the decoding path to enhance the focus on important information. Finally, a DS was designed, and the model was optimized by integrating a joint loss function to further improve the segmentation accuracy. RESULTS: The experiment with AConvLSTM U-Net for jaw cyst lesion segmentation showed a MCC of 93.8443%, a DSC of 93.9067%, and a JSC of 88.5133%, outperforming all the other comparison segmentation models. CONCLUSIONS The proposed algorithm shows a high accuracy and robustness on the jaw cyst dataset, demonstrating its superior performance over many existing methods for automatic segmentation of jaw cyst images and its potential to assist clinical diagnosis.
Humans ; Jaw Cysts/diagnostic imaging* ; Algorithms ; Image Processing, Computer-Assisted/methods* ; Neural Networks, Computer

Transcranial temporal interference stimulation (tTIS) is a novel non-invasive neuromodulation technique with the potential to precisely target deep brain structures. This study explores the neural and behavioral effects of tTIS on the superior colliculus (SC), a region involved in eye movement control, in mice. Computational modeling revealed that tTIS delivers more focused stimulation to the SC than traditional transcranial alternating current stimulation. In vivo experiments, including Ca²⁺ signal recordings and eye movement tracking, showed that tTIS effectively modulates SC neural activity and induces eye movements. A significant correlation was found between stimulation frequency and saccade frequency, suggesting direct tTIS-induced modulation of SC activity. These results demonstrate the precision of tTIS in targeting deep brain regions and regulating eye movements, highlighting its potential for neuroscientific research and therapeutic applications.
Animals ; Superior Colliculi/physiology* ; Transcranial Direct Current Stimulation/methods* ; Eye Movements/physiology* ; Male ; Mice ; Mice, Inbred C57BL

The machine learning is used increasingly and widely in acupuncture prescription optimization, intelligent treatment and precision medicine, and has obtained a certain achievement. But, there are still some problems remained to be solved such as the poor interpretability of the model, the inconsistency of data quality of acupuncture research, and the clinical application of constructed models. Researches in future should focus on the acquisition of high-quality clinical and experimental data sets, take various machine learning algorithms as the basis, and construct professional models to solve various problems, so as to drive the high-quality development of acupuncture research.
Acupuncture Therapy/trends* ; Machine Learning ; Humans ; Algorithms

BACKGROUND: The protective effect of mesenchymal stem cells (MSCs) on cardiac ischemia-reperfusion (I/R) injury has been widely reported. Dental pulp-derived mesenchymal stem cells (DP-MSCs) have therapeutic effects on various diseases, including diabetes and cirrhosis. This study aimed to determine the therapeutic effects of DP-MSCs on I/R injury and elucidate the underlying mechanism. METHODS: Myocardial I/R injury model mice were treated with DP-MSCs or a miR-19a-3p mimic. The infarct volume, fibrotic area, pyroptosis, inflammation level, and cardiac function were measured. Cardiomyocytes exposed to hypoxia-reoxygenation were transfected with the miR-19a-3p mimic, miR-19a-3p inhibitor, or negative control. Pyroptosis and protein expression in the interferon regulatory factor 8/mitogen-activated protein kinase (IRF-8/MAPK) pathway were measured. RESULTS: DP-MSCs protected cardiac function in cardiac I/R-injured mice and inhibited cardiomyocyte pyroptosis. The upregulation of miR-19a-3p protected cardiac function, inhibited cardiomyocyte pyroptosis, and inhibited IRF-8/MAPK signaling in cardiac I/R-injured mice. DP-MSCs inhibited cardiomyocyte pyroptosis and the IRF-8/MAPK signaling by upregulating the miR-19a-3p levels in cardiomyocytes injured by I/R. CONCLUSION DP-MSCs protected cardiac function by inhibiting cardiomyocyte pyroptosis through miR-19a-3p under I/R conditions.
Animals ; MicroRNAs/metabolism* ; Pyroptosis/genetics* ; Mesenchymal Stem Cells/metabolism* ; Myocytes, Cardiac/cytology* ; Mice ; Male ; Mice, Inbred C57BL ; Dental Pulp/cytology* ; Myocardial Reperfusion Injury/therapy* ; MAP Kinase Signaling System/physiology*

Objectives:Comparative analysis of the beagles acute-phase electrocardiographic,hemodynamic,left ventricular flow field status,and energy consumption characteristics of pacing at different sites of conduction system may help to elucidate the scientific mechanism of left bundle branch pacing(LBBP)as a option of physiological pacing therapy.Methods:Eight healthy adult beagles were used in this study.Initially,an active fixation lead was implanted in the right atrial appendage,followed by implantation of another active fixation lead at the right ventricular apex,distal His bundle,and left bundle septal branch,respectively.After connecting a dual-chamber pacemaker,electrocardiographic and acute phase hemodynamic parameters under sinus rhythm,right ventricular apex pacing(RVAP),distal His bundle pacing(DHBP),and LBBP states were collected and analyzed.Three complete cardiac cycles of standard apical three-chamber color Doppler dynamic images were acquired under vector flow mapping(VFM)mode.Offline analysis was performed on obtained parameters including isovolumic contraction period,rapid ejection period,isovolumic relaxation period,rapid filling period,atrial contraction period,and left ventricular intracavitary energy consumption.These parameters were compared under pacing at different sites and the linear correlations of major parameters were analyzed.Results:The QRS duration of baseline intrinsic sinus rhythm,RVAP,DHBP and LBBP were(45.0±4.0)ms,(98.4±6.2)ms,(50.0±4.5)ms and(62.0±4.7)ms,respectively.The LBBP-QRS duration was significantly wider than intrinsic sinus rhythm and DHBP,but significantly narrower than RVAP(all P<0.01).Compared with baseline AOO mode(the pacing rate was performed at 10 beats/min above the intrinsic heart rate),the change of acute phase maximum left ventricular pressure rise rate(LVdP/dtmax)in RVAP,DHBP and LBBP was([-7.89±5.67]% ),([0.74±2.05]% )and([-0.14±3.59]% ),respectively.There was no significant difference in LVdP/dtmax changes between DHBP and LBBP(P=0.667),but both pacing modalities were significantly better than RVAP(all P<0.01).The average energy consumption of the left ventricle under RVAP was significantly higher than that of intrinsic sinus rhythm,DHBP,and LBBP in isovolumic contraction period,rapid ejection period,isovolumic relaxation period,rapid filling period,and atrial contraction period(all P<0.01).However,there was no statistically significant difference in energy consumption among intrinsic sinus rhythm,DHBP,and LBBP during the above five phases(all P>0.05).DHBP and LBBP did not show a significant increase in the number of left ventricular vortices,vortex area,and circulation intensity compared to intrinsic sinus rhythm,and LBBP did not show a significant increase in vortex area and circulation intensity compared to DHBP.Conclusions:Although LBBP canines significantly prolonged the paced QRS duration,it showed no significant differences in acute phase left ventricular hemodynamics,left ventricular flow field status,and energy consumption compared to intrinsic sinus rhythm and DHBP.Performance of LBBP was superior to RVAP.This study may contribute to revealing the theoretical basis of LBBP as a feasible physiological pacing therapy.

OBJECTIVE To study the mechanism of Wenshen Tongdu Recipe in promoting the recovery of motor function in rats with spinal cord injury.METHODS A total of 144 SD rats were randomly divided into sham operation group,model group,predni-sone group,low-dose Wenshen Tongdu Recipe group,medium-dose Wenshen Tongdu Recipe group,high-dose Wenshen Tongdu Recipe group,3BDO group,and 3BDO+Wenshen Tongdu Recipe group(medium dose).The rat spinal cord injury model was estab-lished by modified Allen's method.Intervention began 1 day after modeling,and the drug was administered continuously for 14 days.During the drug administration period,the motor function of the rats in each group was evaluated by Basso-Beattie-Bresnahan(BBB)score and inclined plane test.On the 3rd,7th and 14th days after modeling,the pathological changes of the spinal cord tissues of the rats in each group were observed by HE staining;the expression levels of inflammatory factors IL-1β,IL-6,IL-4 and IL-10 in the serum of the rats in each group were detected by ELISA;the expression of Beclin 1,LC3B and p62 proteins was detected by immu-nohistochemistry;the expression of CD16 and CD206 proteins was detected by immunofluorescence staining;the expression of autoph-agy-related molecules(Beclin 1,LC3B)and Akt/mTOR pathway-related proteins in the spinal cord tissues was detected by Western blot.RESULTS Compared with the model group,the BBB score and angle of the inclined board test of rats in the medium-dose Wenshen Tongdu Recipe group were increased,and the disordered arrangement of spinal cord tissue,spinal cord vacuoles and inflam-matory infiltration were significantly improved,especially on the 14th day.Compared with the sham operation group,the expression levels of serum IL-1β and IL-6 in the model group increased(P<0.01),and the expression levels of IL-4 and IL-10 decreased(P<0.05,P<0.01);compared with the model group,the levels of IL-1β and IL-6 in the Wenshen Tongdu Recipe group were signifi-cantly decreased(P<0.01),and the levels of IL-4 and IL-10 were significantly increased(P<0.05,P<0.01);compared with the Wenshen Tongdu Recipe group,the serum IL-1β and IL-6 concentrations of mice in the 3BDO group increased(P<0.01),and the level of IL-10 decreased(P<0.05).Compared with the sham operation group,the M1/M2 ratio,P62 protein expression,p-Akt/Akt and p-mTOR/mTOR ratios in the spinal cord tissue of the rats in the model group were significantly increased(P<0.05,P<0.01),and the relative protein expression of Beclin1 was decreased(P<0.01);compared with the model group,the M1/M2 ratio,p-Akt/Akt and p-p70S6K/p70S6K ratios in the Wenshen Tongdu Recipe group were significantly decreased(P<0.01).Compared with the model group,the Beclin1 protein level in the 3BDO group was decreased,and the p-Akt/Akt and p-mTOR/mTOR ratios were increased(P<0.05,P<0.01).Compared with the Wenshen Tongdu Recipe group,the M1/M2 ratio in the 3BDO group and the 3BDO+Wen-shen Tongdu Recipe group increased(P<0.01),the positive rates of Beclin1 and LC3B proteins in the 3BDO group decreased signifi-cantly(P<0.01),and the p-p70S6K/p70S6K ratio in the 3BDO+Wenshen Tongdu Recipe group increased significantly(P<0.01).CONCLUSION Wenshen Tongdu Recipe may regulate microglial polarization through Akt/mTOR signaling pathway to acti-vate autophagy,promote the secretion of anti-inflammatory factors,reduce the release of pro-inflammatory factors,alleviate neuroin-flammatory response,and thus promote spinal cord injury repair.

Objective:To explore the effect of necroptosis inhibitor necrosulfonamide (NSA) on traumatic brain injury (TBI) mouse model and BV2 cell pyroptosis model and their mechanisms.Methods:(1) In vivo experiments: 50 mice were randomly divided into sham-operated group, TBI group, TBI+1 mg/kg NSA group, TBI+5 mg/kg NSA group, and TBI+10 mg/kg NSA group, with 10 mice in each group. TBI model was established using a modified Feeney's weight-drop method; 4 h after modeling, 90% corn oil, 1 mg/kg NSA, 5 mg/kg NSA, or 10 mg/kg NSA was administered into the mice, respectively. Mice in the sham-operated group only had circular bone window opened without being subjected to impact. At 48 hours after modeling, neurological function was evaluated by modified neurological function score (mNSS), serum lactate dehydrogenase (LDH) content was detected by LDH detection kit, contents of interleukin (IL)-18, IL-1β and tumor necrosis factor-α (TNF-α) in the brain tissues were detected by enzyme-linked immunosorbent assay (ELISA), and expressions and localizations of ionized calcium binding adaptor molecule 1 (IBA-1), cysteinyl aspartate specific proteinase-1 (Caspase-1) p20 and gasdermin D (GSDMD) in the injured parietal cortex were detected by double immunofluorescent staining. (2) In vitro experiments: BV2 cells were divided into control group, lipopolysaccharide (LPS)+adenosine triphosphate (ATP)+dimethyl sulfoxide (DMSO) group, LPS+ATP+5 μmol/L NSA group, LPS+ATP+10 μmol/L NSA group, and LPS+ATP+15 μmol/L NSA group. Cells in the latter 4 groups were induced by LPS+ATP to establish BV2 cell pyroptosis model, and incubated with 2 μL DMSO, 5 μmol/L NSA, 10 μmol/L NSA, and 15 μmol/L NSA for 1 hour, respectively; cells in the control group were cultured conventionally. Contents of LDH, IL-1β, IL-18, and TNF-α in the cell culture supernatant were detected by ELISA; pyroptosis was detected by calcein acetoxymethyl ester (CAM)/propidium iodide (PI) double staining; protein expressions of nucleotide binding domain-like receptor protein 3 (NLRP3), Caspase-1 p20, GSDMD, and N-terminal fragment of GSDMD (GSDMD-N) were detected by Western blotting. Results:(1) Compared with the TBI group, the TBI+1 mg/kg NSA group, TBI+5 mg/kg NSA group and TBI+10 mg/kg NSA group had decreased mNSS score and serum LDH content, decreased IL-1β and IL-18 contents in the brain tissues and number of Caspase-1 p20 + cells in the injured parietal cortex, successively, with significant differences ( P<0.05). Compared with the TBI group ([287.80±12.26] cells/mm 2), the TBI+1 mg/kg NSA group, TBI+5 mg/kg NSA group, and TBI+10 mg/kg NSA group had decreased number of Iba-1 +GSDMD + cells in the injured parietal cortex ([213.70±11.87] cells/mm 2, [205.30±9.15] cells/mm 2, [131.70±13.69] cells/mm 2),successively, with significant differences ( P<0.05). Compared with the TBI group, the TBI+5 mg/kg NSA group and TBI+10 mg/kg NSA group had significantly decreased number of Iba-1 + cells in the injured parietal cortex, and the TBI+10 mg/kg NSA group had significantly decreased TNF-α content in the brain tissues and number of GSDMD + cells in the injured parietal cortex ( P<0.05). Compared with the TBI group ([247.20±9.88] cells/mm 2), the TBI+10 mg/kg NSA group had significantly decreased number of Iba-1 +Caspase-1 p20 + cells in the injured parietal cortex ([181.70±9.37] cells/mm 2, P<0.05). (2) Compared with the LPS+ATP+DMSO group, the LPS+ATP+5 μmol/L NSA group, LPS+ATP+10 μmol/L NSA group, and LPS+ATP+15 μmol/L NSA group had decreased IL-18 content in the supernatant, successively, with significant differences ( P<0.05); and compared with the LPS+ATP+DMSO group, the LPS+ATP+10 μmol/L NSA group and LPS+ATP+15 μmol/L NSA group had significantly decreased contents of LDH, IL-1β, and TNF-α in the supernatant and ratio of PI +/CAM + cell counts ( P<0.05). Compared with the LPS+ATP+DMSO group (2.62±0.50), the LPS+ATP+10 μmol/L NSA group and LPS+ATP+15 μmol/L NSA group had significantly decreased Caspase-1 p20 protein expression (1.36±0.14, 1.32±0.07, P<0.05). Compared with the LPS+ATP+DMSO group (5.00±1.67), the LPS+ATP+5 μmol/L NSA group and LPS+ATP+15 μmol/L NSA group had significantly decreased GSDMD protein expression (1.42±0.26, 1.68±0.32, P<0.05). Compared with the LPS+ATP+DMSO group (2.28±0.24), the LPS+ATP+15 μmol/L NSA group had significantly decreased GSDMD-N protein expression (1.23±0.08, P<0.05). Conclusion:NSA can inhibit microglial pyroptosis after TBI by inhibiting the Caspase-1 p20/GSDMD pathway, thereby playing a neuroprotective role.

Objectives:Comparative analysis of the beagles acute-phase electrocardiographic,hemodynamic,left ventricular flow field status,and energy consumption characteristics of pacing at different sites of conduction system may help to elucidate the scientific mechanism of left bundle branch pacing(LBBP)as a option of physiological pacing therapy.Methods:Eight healthy adult beagles were used in this study.Initially,an active fixation lead was implanted in the right atrial appendage,followed by implantation of another active fixation lead at the right ventricular apex,distal His bundle,and left bundle septal branch,respectively.After connecting a dual-chamber pacemaker,electrocardiographic and acute phase hemodynamic parameters under sinus rhythm,right ventricular apex pacing(RVAP),distal His bundle pacing(DHBP),and LBBP states were collected and analyzed.Three complete cardiac cycles of standard apical three-chamber color Doppler dynamic images were acquired under vector flow mapping(VFM)mode.Offline analysis was performed on obtained parameters including isovolumic contraction period,rapid ejection period,isovolumic relaxation period,rapid filling period,atrial contraction period,and left ventricular intracavitary energy consumption.These parameters were compared under pacing at different sites and the linear correlations of major parameters were analyzed.Results:The QRS duration of baseline intrinsic sinus rhythm,RVAP,DHBP and LBBP were(45.0±4.0)ms,(98.4±6.2)ms,(50.0±4.5)ms and(62.0±4.7)ms,respectively.The LBBP-QRS duration was significantly wider than intrinsic sinus rhythm and DHBP,but significantly narrower than RVAP(all P<0.01).Compared with baseline AOO mode(the pacing rate was performed at 10 beats/min above the intrinsic heart rate),the change of acute phase maximum left ventricular pressure rise rate(LVdP/dtmax)in RVAP,DHBP and LBBP was([-7.89±5.67]% ),([0.74±2.05]% )and([-0.14±3.59]% ),respectively.There was no significant difference in LVdP/dtmax changes between DHBP and LBBP(P=0.667),but both pacing modalities were significantly better than RVAP(all P<0.01).The average energy consumption of the left ventricle under RVAP was significantly higher than that of intrinsic sinus rhythm,DHBP,and LBBP in isovolumic contraction period,rapid ejection period,isovolumic relaxation period,rapid filling period,and atrial contraction period(all P<0.01).However,there was no statistically significant difference in energy consumption among intrinsic sinus rhythm,DHBP,and LBBP during the above five phases(all P>0.05).DHBP and LBBP did not show a significant increase in the number of left ventricular vortices,vortex area,and circulation intensity compared to intrinsic sinus rhythm,and LBBP did not show a significant increase in vortex area and circulation intensity compared to DHBP.Conclusions:Although LBBP canines significantly prolonged the paced QRS duration,it showed no significant differences in acute phase left ventricular hemodynamics,left ventricular flow field status,and energy consumption compared to intrinsic sinus rhythm and DHBP.Performance of LBBP was superior to RVAP.This study may contribute to revealing the theoretical basis of LBBP as a feasible physiological pacing therapy.