library_construction_protocol: Rat carotid bodies (CBs) were dissociated by enzymatic and mechanical treatment. Briefly, CBs were dissociated in PBS solution containing 0.6 mg/ml collagenase type II (Sigma), 0.35 U/ml porcine elastase (Calbiochem), 0.3 mg/ml trypsin (Sigma), and 10 ul/ml of 5 mM CaCl2 solution, for 25 min at 37ºC, using a shaker. Once dissociated, single cells were resuspended in a staining solution composed by (for 50 ml): 44 ml L15 medium (Gibco), 0.5 ml penicillin/streptomycin (Gibco), 0.5 ml 1M HEPES buffer (Gibco), 0.1 g BSA (Sigma), and 5 ml distilled and deionized water. Dispersed cells were used for single cell transcriptome analysis . Single-cell RNA sequencing (scRNA-seq) was performed with the 10x Genomics Chromium Single Cell 3′ Kit (v.3) according to the standard protocol. Libraries were sequenced on an Illumina NovaSeq 6000 sequencing platform.