EDN1 and asthma: In the group of healthy volunteers we observed the lowest levels of ET-1 in EBC, but this difference was statistically significant only comparing with asthmatics with EIB (asthma with EIB vs. healthy volunteers: 0.59 fmol/ml ± 0.18, p = 0.018; asthma without EIB vs. healthy volunteers: p = 0.13).