Aerobic Exercise Training Activating the Large-conductance Ca²⁺-activated ^K+ Channels in Rat Thoracic Aorta Smooth Muscle Cells

Objective:The purpose of this study was to investigate the effects of aerobic exercise training on the activity of large-conductance Ca2+-activated K+ channels(BKCa) in thoracic aorta smooth muscle cells(SMCs).Methods:Twenty-four 2-month-old male Wistar rats were assigned to 3 groups randomly,sedentary group(SED),low-frequency exercise group(exercise 3d/w,EX1),and high-frequency exercise group(exercise 5d/w,EX2).After 12 weeks,the segment of thoracic aorta was carefully dissected free,and separated into smooth muscle cells by two steps digestion.Results:Inside-out patch clamp recording on aortic SMCs showed that exercise training did not affect the single channel conductance,but significantly increased the open probability(Po) of BKCa channels.Moreover,exercise training decreased the mean closed time(Tc) and increased the mean open time(To) of BKCa channels.This effect was more significant in EX2 group than that in EX1 group.Conclusion:These data suggest that regular aerobic exercise can activate the BKCa channels in the rat thoracic aorta SMCs,which is in a frequency-dependent manner when the intensity and duration of exercise is kept consistent.