Table 1.

Patient characteristics

	Nonsmokers	Smokers	COPD
n	9	9	9
Age (years)	66.4 ± 12.72	59.2 ± 7.6	65.4 ± 6.6
Sex (♂ – ♀)	7 – 2	4 – 5	5 – 5
Pack years smoking	N/A	29.25 ± 3.3	38.32 ± 26.92
FEV1 (L)	4.02 ± 0.48	3.12 ± 0.78	1.76 ± 0.45
FEV1 (% Predicted)	104.23 ± 7.28	101.5 ± 4.51	77 ± 21.97
FEV1/FVC (%)	78.89 ± 5.98	77.57 ± 3.32	38.88 ± 15.75
PC20 (mg·mL−1)	> 16	> 16	Too severe

FEV₁, forced expiratory volume in 1 s; FVC, forced vital capacity; PC₂₀, provocative concentration of methacholine causing a 20% fall in FEV₁. Data shown as mean ± SEM.