A novel mouse skeletal muscle-nerve preparation and in vitro model of ischemia

The majority of patients in pain clinics are treated for muscle pain yet methods to study it in animals are relatively weak compared to methods to study skin pain. Here we describe an in vitro muscle-nerve preparation and model of muscle ischemia and contractile fatigue in mice. Timed muscle contraction is electrically evoked, while single unit activity of muscle sensory neurons and muscle contractile force are simultaneously recorded. The muscle is placed in a small (<1 mL) chamber where oxygen levels can be manipulated, drugs can be applied, and the extracellular milieu can be highly controlled. We demonstrate that we can record from sensory afferents that have the properties expected of ischemic nociceptors. This method serves for studying the neuronal and molecular mechanisms underlying ischemic pains such as angina, intermittent claudication, and sickle cell crisis.