Type 3

The SGCs of DRG (C1-T2) from neonatal Sprague-Dawley rats were prepared as follows. Briefly, 1- to 3-day-old neonatal rats were anesthetized, and DRGs were harvested in ice-cold Hank’s balanced salt solution (HBSS). DRGs were removed with fine dissecting forceps from the inner side of each half of the dissected vertebrae together with the dorsal and ventral roots and attached spinal nerves. After removing the attached nerves and the surrounding connective tissue, DRGs were incubated with trypsin (2.5 mg/mL; type III, Sigma), collagenase (1.0 mg/mL; type IA, Sigma), and DNase (0.1 mg/mL; type IV, sigma) at 37°C in a shaking bath for 15 min. Subsequently, 10% fetal bovine serum (FBS) was added to stop enzymatic digestion. After centrifuging (5 min, 1000 rpm), the remaining ganglia were dissociated into single cells by trituration with heat-polished Pasteur pipettes and passed through nylon mesh with a pore diameter size of 100 μm. Isolated cells were suspended in Dulbecco’s Modified Eagle Medium (DMEM) (Gibco by Life Technologies) supplemented with 10% FBS and 1% penicillin/streptomycin. These cells were seeded on uncoated 35 mm dishes at 37°C with 5% CO₂ for up to 3 days. The media were completely changed every day. Before calcium fluorescence imaging, DRG SGCs were cultured with or without baicalin (10 μM) for 24 h. The experiments were performed at room temperature (20–30°C).

Calix[4]resorcinol VC10 was synthesized by the reaction of tetra-(bromomethyl)calix[4]resorcinol with monomethylviologen using the procedure described in the literature [26 (link)]. Haloperidol, Hal (Alfa Aesar), D₂O (99.9 atom% D, Carl Roth GmbH), mucin from porcine stomach, and PGM (Type III, bound sialic acid 0.5–1.5%, partially purified powder, Sigma-Aldrich (St. Louis, MO, USA)) were purchased and used without further purification. Deionized, ultrapure water with a resistivity of 18.2 MΩ was generated using a Direct Q-5 UV water purification system from Millipore SAS (Molsheim, France) and was used throughout this work.