Fig. 2. Relative expression of the selected oxygen-sensing and signaling genes in the human carotid body. Gene expression was determined by real-time polymerase chain reaction (PCR). Data are normalized to the reference genes (see Materials and Methods) according to the common ΔCtmethod using the formula 2ΔCttarget gene (40 − Cttarget)/2ΔCtreference gene (40 −Ctreference gene)and related to the expression of tyrosine hydroxylase (TH) ± SEM. Ctis mean critical threshold, the PCR cycle number at which the increase in fluorescence is exponential. The PCR efficiency (amplification rate at each cycle) was assumed to be close to 2. BK = large-conductance potassium channel; GABA =γ-aminobutyric acid; HO-2 = heme oxygenase-2; nAChR = nicotinic acetylcholine receptor; TASK-1, TWIK-related acid sensitive K+channel-1.
