Repeated Measurement of Respiratory Muscle Activity and Ventilation in Mouse Models of Neuromuscular Disease

Summary

This paper introduces a method for repeated measurements of ventilation and respiratory muscle activity in a freely behaving amyotrophic lateral sclerosis (ALS) mouse model throughout disease progression with whole-body plethysmography and electromyography via an implanted telemetry device.

Abstract

Accessory respiratory muscles help to maintain ventilation when diaphragm function is impaired. The following protocol describes a method for repeated measurements over weeks or months of accessory respiratory muscle activity while simultaneously measuring ventilation in a non-anesthetized, freely behaving mouse. The technique includes the surgical implantation of a radio transmitter and the insertion of electrode leads into the scalene and trapezius muscles to measure the electromyogram activity of these inspiratory muscles. Ventilation is measured by whole-body plethysmography, and animal movement is assessed by video and is synchronized with electromyogram activity. Measurements of muscle activity and ventilation in a mouse model of amyotrophic lateral sclerosis are presented to show how this tool can be used to investigate how respiratory muscle activity changes over time and to assess the impact of muscle activity on ventilation. The described methods can easily be adapted to measure the activity of other muscles or to assess accessory respiratory muscle activity in additional mouse models of disease or injury.

Introduction

Accessory respiratory muscles (ARMs) increase ventilation during times of high demand (e.g., exercise) and help to maintain ventilation when diaphragm function is compromised following injury or disease^1,2. Although changes in diaphragm function have been well described in amyotrophic lateral sclerosis (ALS) patients and mouse models^3,4,5,6, much less is known about the activity or function of ARMs in ALS. However, one study suggested that ALS patients that recruit ARMs have....

Protocol

Experimental procedures were approved by the Cincinnati Children's Hospital Medical Center Institutional Animal Care and Use Committee and conducted in compliance with the NIH Guide for the care and use of laboratory animals.

1. Preparing for Telemetry Device Implant Surgery

1. Put on personal protective equipment (i.e., scrubs, shoe covers, gown, hair net, mask, and surgical gloves).
   NOTE: This surgery requires a sterile field.
2. Turn on the incubator (servo-controlled humidifier/infant incubator set to 29 ​°C) and line it with dry, white towels to allow proper warming for recovery.
3. Prior to surgery, st....

Results

The described protocol was used to implant a telemetry device and to record scalene and trapezius EMG, WBP, and video of a SOD1(G93A) ALS model mouse. Periods in which the animal is inactive (e.g., does not move) were identified using the video recording and confirmed by the lack of movement-related activity in the WBP trace (Figure 3A). Inactive periods include time spent in REM or non-REM sleep, as well as time spent awake but still (Figure 3A).......

Discussion

The procedure demonstrated here allows for the noninvasive (after initial surgical implantation of the transmitter) measurement of respiratory muscle activity and ventilation over many months in the same animal. This technique has several advantages over standard EMG techniques in anesthetized mice: 1) the experiments require fewer mice and provide the ability to record data from the same site in a single mouse across disease stages (instead of using multiple mice at different disease stages); 2) data analysis can be per.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
B6.Cg-Tg (SOD1*G93A)1 Gur/J	Jackson Laboratory	4435
Plethysmography Chamber	Buxco Respiratory Products/ Data Sciences International	601-1425-001
Telemetry Receivers (Model RPC-1)	Data Sciences International	272-6001-001
Bias Flow Pump (Model BFL0500)	Data Sciences International	601-2201-001
ACQ-7000 USB	Data Sciences International	PNM-P3P-7002XS
Dataquest A.R.T. Data Exchange Matrix	Data Sciences International	271-0117-001
New Ponemah Analysis System	Data Sciences International	PNM-POST-CFG
Ponemah Physiology Platform Acqusition software v5.20	Data Sciences International	PNM-P3P-520
Ponemah Unrestrained Whole Breath Plethysmography analysis package v5.20	Data Sciences International	PNM-URP100W
Configured Ponemah Software System	Data Sciences International	PNM-P3P-CFG
Analysis Module (URP)	Data Sciences International	PNM-URP100W
Universal Amplifier	Data Sciences International	13-7715-59
Sync Board	Data Sciences International	271-0401-001
Sync Cable	Data Sciences International	274-0030-001
Transducer-Pressure Buxco	Data Sciences International	600-1114-001
Flow Meter	Data Sciences International	600-1260-001
Magnet and Radio included in F20-EET Starter Kit	Data Sciences International	276-0400-001
Axis P1363 Video Camera	Data Sciences International	275-0201-001
Terg-A-Zyme	Fisher Scientific	50-821-785	Enzyme Detergent
Actril	Minntech Corporation	78337-000	Chemical Sterilant
Stereo Dissecting Microscope (Model MEB126)	Leica	10-450-508
Servo-Controlled Humidifier/Infant Incubator	OHMEDA Ohio Care Plus	6600-0506-803
TL11M2-F20-EET Transmitters	Data Sciences International	270-0124-001
Dumont #2 Laminectomy Forceps - Standard Tips/Straight/12 cm (x2)	Fine Scientific Instruments	11223-20	For handling wires
Dumont #2 Laminectomy Forceps - Standard Tips/Straight/12 cm (x2)	Fine Scientific Instruments	11223-20	For surgery
Narrow Pattern Forceps- Serrated/Curved/12 cm	Fine Scientific Instruments	17003-12
Spring Scissors - Tough Cut/Straight/Sharp/12.5 cm/6 mm Cutting Edge	Fine Scientific Instruments	15124-12
Tissue Separating Scissors - Straight/Blunt-Blunt/11.5 cm	Fine Scientific Instruments	14072-10
Fine Scissors - Tough Cut/Curved/Sharp-Sharp/9 cm	Fine Scientific Instruments	14058-11	For cutting wires and clipping nails
Scalpel Handle #3	World Precision Instruments	500236
Scalpel Blade	Fine Scientific Instruments	10010-00	For preparing lead caps
Polysorb Braided Absorbable suture	Coviden	D4G1532X	For coiling transmitter leads
Gluture	Zoetis Inc.	6606-65-1	Cyanoacrylate adhesive
3 mL Syring Slip Tip - Soft	Vitality Medical	118030055
25 G Needle (x2)	Becton Dickinson and Co.	305-145
Cotton Tipped Applicators	Henry Schein Animal Health	100-9175
Andis Easy Cut Hair Clipper Set	Andis	049-06-0271	Electrical Razor sold at Target
Isoflurane	Henry Schein Animal Health	29404	Anesthetic
Isopropyl Alcohol 70%	Priority Care 1	MS070PC
Dermachlor 2% Medical Scrub (chlorohexidine 2%)	Butler Schein	55482
Artificial Tears	Henry Schein Animal Health	48272	Lubricant Opthalmic Ointment
Vacuum grease	Dow Corning Corporation	1597418
Water Blanket	JorVet	JOR784BN