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. 2013 Mar 28;144(2):498–506. doi: 10.1378/chest.13-0274

Figure 3.

Figure 3.

Ion transport activity in smokers with and without COPD. A, Cystic fibrosis transmembrane conductance regulator (CFTR) activity estimated in the lower airway by the change in PD following perfusion with chloride-free isoproterenol. **P < .005; ***P = .054. B, Baseline potential difference as determined by the stable PD following perfusion with Ringer solution. Baseline PD was lower in both healthy smokers (−7.71 ± 0.88) and COPD smokers (−7.33 ± 1.30) than in healthy nonsmokers (−12.61 ± 1.94). *P < .05. C, Amiloride-sensitive PD determined by the change in PD with amiloride perfusion. Amiloride-sensitive PD was lower in healthy smokers (4.04 ± 0.78 mV) and COPD smokers (2.49 ± 0.72 mV) than in healthy nonsmokers (8.79 ± 2.09 mV); COPD former smokers again were intermediate but not statistically different from healthy control patients (5.08 ± 1.50). *P < .05; **P < .005. PD = potential difference.