Figure 1.

Comparison of organic cation transporter mRNA expression levels in human tissues and cells. Relative mRNA expression levels of the membrane potential sensitive organic cation transporters (OCT1, OCT2, and OCT3) and the pH-dependent organic cation/carnitine transporters (OCTN1 and OCTN2) were measured using quantitative RT-PCR. Tracheas and large bronchi (⩾ third generation) were obtained from human donors without preexisting lung disease (n of donors = 4), and from patients with cystic fibrosis (ΔF508/ΔF508 homozygote and ΔF508/D1152H heterozygote) (n of donors = 2). RNA was extracted from scraped airway epithelium and/or cells cultured and re-differentiated at the ALI. Placenta, kidney, and liver RNA samples were obtained from a single donor subject. Expression data are indicated relative to the sample (calibrator) with the highest expression level of the respective gene: liver for OCT1, kidney for OCT2, OCTN1, and OCTN2, and placenta for OCT3, respectively. Bars indicate the average of triplicate quantitative RT-PCR measurements. Error bars indicate SEM for samples obtained from four different human donors. ND = not detectable level.