Electrophysiology Recording of Parasympathetic Neurons

Tracheas were removed from anesthetized mice and were submerged in room temperature Krebs buffer containing (in mM): 125 NaCl, 21.4 NaHCO₃, 11.1 D-glucose, 2.5 KCl, 1.2 MgCl₂, 2.4 CaCl₂, 1.2 NaH₂PO₄, ∼305 mOsm, and incubated in 0.02 mg/ml Liberase (Thermolysin Medium; Roche) for 30 minutes. Tracheas were then washed in artificial cerebrospinal fluid (aCSF) for another 20 minutes while being saturated with 95% O₂/5% CO₂. Recordings were obtained at near-physiological temperature (32–34°C) from slices superfused with oxygenated aCSF.