Objective Large-conductance Ca2+-activated K+ (BKCa) channels play a critical role in regulating vascular tone.In this study, we investigated the effects of moderate exercise training (ET) on the expression of BKCa channels proteins in thoracic and mesenteric arteries of aged rats.Methods OldWistar rats (19 months old)were randomly assigned to sedentary (O-SED) and exercise-trained groups (O-ET).The O-ET rats underwent a progressive treadmill exercise-training programme(15 m/min, 60 min/day, 5 days/week, 12 weeks).Young rats (2months old) were used for comparison.Western immunoblotting was performed to study expression levels of BKCa channel proteins.Results The α subunit of the BKCa channel was reduced not obviously, however, theβ1 subunit was reduced significantly in thoracic and mesenteric arteries of old compared with young rats.ET increased the expression level of α subunits unobviously but increased the expression level of 1β1 subunits significantly in thoracic and mesenteric arteries, compared with SED rats.Conclusion Moderate exercise training (ET) may be beneficial in restoring age-related decline invasodilatory properties of thoracic and mesenteric arteries mediated by BKCa channels.