Protocol for simultaneous non-invasive electrocardiogram and respiratory plethysmography recordings in mice

Figures

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  Figure 1. Preparation and placement of mouse ECG leads prior to plethysmography recording Stepwise depiction of the anesthesia, electrode placement, and chamber transfer for simultaneous ECG and plethysmography recordings. (Left) Mouse under isoflurane anesthesia for lead positioning; (Center) Dimensions and details of custom-cut kinesiology tape securing the electrodes; (Right) Proper placement and routing of ECG leads during recovery, ensuring thoracic fixation and dorsal wire orientation to minimize interference and chewing.

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  Figure 2. A mouse prepared for recording and wrapped with kinesiology tape The leads are secured away from the animal’s mouth to make connecting to the system easier and reduce the likelihood of the animal chewing on the wire.

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  Figure 3. Fully recovered from anesthesia, the mice are ready to be introduced into the plethysmography chamber

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  Figure 4. Connecting the leads attached to the animal to the wires secured through the chamber

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  Figure 5. Recording both plethysmography and ECG data from the animal under normoxic conditions

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  Figure 6. Experimental setup for plethysmography acclimation Schematic overview of the whole-body plethysmography system during the initial acclimation phase. The conscious mouse is placed in the chamber on a heat pad, and respiratory activity is recorded using a spirometer and flow-controlled gas system. Data acquisition is performed via PowerLab hardware, with real-time respiratory traces visualized in LabChart. The setup also includes temperature monitoring to maintain physiological condition.

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  Figure 7. Acclimation Day Two Making sure the animal is used to having wires in the plethysmograph chamber and does not see them as a new object to play with or chew on helps preserve your chamber wires during recordings and relaxes the animal.

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  Figure 8. Acclimation Day Three Make sure everything is running smoothly and the animals are comfortable with the setup. These recordings can also be used as a baseline for any further analysis.

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  Figure 9. The plethysmography signal is in red, and the ECG signal is in blue These recordings are under normoxic conditions from 3xTg-AD mice. (A) A good recording with clear breathing and ECG signal. (B) Clear breathing acquisition, but the ECG wrap is loose resulting in poor ECG data. (C) Both breathing and ECG signals are usable, but the wrap may be restricting breathing. (D) This is an example of when you should pull an animal out of the chamber. Repeated sighs in combination with erratic heart beats are not good physiological signs and leaving the animal in the chamber can lead to death. Besides the ECG signal in panel B each of these signals can be used for analysis.