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In This Article

  • Summary
  • Abstract
  • Introduction
  • Protocol
  • Representative Results
  • Discussion
  • Acknowledgements
  • Materials
  • References
  • Reprints and Permissions

Summary

Presented here is a surgical procedure for permanent ligation of the left coronary artery in mice. This model can be used to investigate the pathophysiology and associated inflammatory response after myocardial infarction.

Abstract

Ischemic heart disease and subsequent myocardial infarction (MI) is one of the leading causes of mortality in the United States and around the world. In order to explore the pathophysiological changes after myocardial infarction and design future treatments, research models of MI are required. Permanent ligation of the left coronary artery (LCA) in mice is a popular model to investigate cardiac function and ventricular remodeling post MI. Here we describe a less invasive, reliable, and reproducible surgical murine MI model by permanent ligation of the LCA. Our surgical model comprises of an easily reversible general anesthesia, endotracheal intubation that does not require a tracheotomy, and a thoracotomy. Electrocardiography and troponin measurement should be performed to ensure MI. Echocardiography at day 28 after MI will discern heart function and heart failure parameters. The degree of cardiac fibrosis can be evaluated by Masson's trichrome staining and cardiac MRI. This MI model is useful for studying the pathophysiological and immunological alterations after MI.

Introduction

Cardiovascular disease is a major public health concern that claims 17.9 million lives each year, accounting for 31 percent of global mortality1. The most prevalent type of cardiovascular anomaly is coronary heart disease, and myocardial infarction (MI) is one of the major manifestations of coronary heart disease2. MI is usually caused by thrombotic occlusion of a coronary artery due to the rupture of a vulnerable plaque3. The resulting ischemia causes profound ionic and metabolic changes in the affected myocardium, as well as a rapid decrease in systolic function. MI results in the death of cardi....

Protocol

The present study protocol was reviewed and approved by the Institutional Animal Care and Use Committee (IACUC) of the University of Pittsburgh. Eight (sham n = 4 and MI n = 4) 1-year-old female C57BL/6J mice weighing 24-30 g were used for these experiments. Approximately 100% and at least 80% of mice survived in the first 24 h and 28 days, respectively.

1. Preparation and endotracheal intubation of the mice

  1. Preheat a bead sterilizer (see Table of Materials.......

Representative Results

Figure 1 demonstrates the representative active ECG and respiration signals during the echocardiographic evaluation of sham (Figure 1A) and MI (Figure 1B) mice. Verification of active ECG and respiration signals are important before acquiring the echocardiographic data. Figure 2 shows echocardiographic measurement of cardiac functional parameters following 28 days after LCA ligation.

Discussion

The murine model of MI is gaining popularity in cardiovascular research laboratories, and this study describes a reproducible and clinically relevant MI model. This protocol improves the LCA ligation process in several ways. To begin with, the use of injectable pre-operative anesthetics such as xylazine/ketamine or sodium pentobarbital14,15 is avoided. Only isoflurane anesthesia was used, which helps enhance animal survival rates (>80% survival 28 days after .......

Acknowledgements

This work was supported by National Institute of Health grants (R01HL143967, R01HL142629, R01AG069399, and R01DK129339), AHA Transformational Project Award (19TPA34910142), AHA Innovative Project Award (19IPLOI34760566), and ALA Innovation Project Award (IA-629694) (to PD).

....

Materials

NameCompanyCatalog NumberComments
22 G catheter needleExel INT26741Thoracentesis
24 G catheter needleExel INT26746Endotracheal intubation
4-0 nylon sutureCovetrus29263Suturing of muscles and skin
8-0 nylon sutureS&T3192Ligation of LAD
Anesthetic VaporizersVet equipVE-6047Anesthetic support
Animal physiology monitorFujifilmVEVO 3100Monitor heart rate,respiration rate and body temperature
Betadine solutionPBS animal health11205Antispetic
BuprenorphineCovetrus55175Analgesic
Disecting microscopeOMANOOM2300S-V7Binocular
Electric razorWahl79300-1001MShaving
Electrode gelParker LaboratoriesW60698LElectrically conductive gel
EthanolDecon Laboratories22-032-601Disinfectant
ForcepsFST11065-07Stainless Steel
GauzeCurityCAR-6339-PKSterile
Heat lampSatcoS4998Post surgery care
Heating padKent scientificSurgi-MTemperature control
Hot Bead sterilizerGerminator 50011503Sterilization of surgical instrument
IsofluraneCovetrus29405Anesthesia
Masson’s trichrome staining kitThermoscientific87019Measurement of cardiac Fibrosis
Micro Needle HolderFST12500-12Stainless Steel
Micro scissorsFST15000-02Stainless Steel
Ophthalmic ointmentDechraPuralube VetSterile occular lubricant
Scanning GelParker LaboratoriesAquasonic 100Aqueous ultrasound transmission gel
ScissorsFST14060-11Stainless Steel
Small Animal LaryngoscopePenn-CenturyModel LS-2-MIlluminating the oropharynx
Small animal ventilatorHarvard apparatus557058Ventilator support
Surgical lightCole parmer41723Illuminator Width (in): 7
Vevo 3100 preclinical imaging platformFujifilmVEVO 3100Echocardiography
VevoLAB softwareFujifilmVevoLAB 3.2.6Echocardiography data analysis

References

  1. Virani, S. S., et al. Heart disease and stroke statistics-2021 update: a report from the American Heart Association. Circulation. 143 (8), 254 (2021).
  2. Mendis, S., et al. World Hea....

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Left Coronary Artery LigationSurgical Murine ModelMyocardial InfarctionMouse ModelMIAnesthesiaBuprenorphineIntubationVentilatorThoracotomyLeft VentricleLeft Coronary Artery

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