Effects of aerobic exercise training on large-conductance Ca2+-activated K+ channels in rat cerebral artery smooth muscle cells

Purpose

Large-conductance Ca²⁺-activated K⁺ (BK_Ca) channels provide a negative feedback that regulates vascular tone in the brain circulation. This study investigated the effects of aerobic exercise on gating properties of BK_Ca channels in rat cerebral artery.

Methods

Rats were subjected to moderate-intensity exercise at low (EX-3d/w) and high (EX-5d/w) training volume on a motor-driven treadmill, and compared with age-matched sedentary animals (SED). Inside–out (I/O) patch clamp recording was performed to measure gating properties of the BK_Ca channel.

Results

Aerobic exercise induced a reduction in heart rate and body weight in both training groups. Exercise increased the channel activity, which was more pronounced in EX-5d/w than that in EX-3d/w group. Kinetic analysis revealed that (1) the contribution of short open states was elevated and the duration of both short and long open states were extended by exercising in EX-3d/w; (2) Ex-3d/w had no significant change on conformation of close states; (3) EX-3d/w increased the mean open time without changing mean closed time; (4) EX-5d/w increased both the contribution and duration of long open states; (5) EX-5d/w increased channel mean open time while decreased mean closed time.

Conclusion

The results suggest that regular aerobic exercise may enhance BK_Ca channel activity in cerebral arterial myocytes by changing its biophysical properties, and the electrical remolding induced by exercise may be training volume-dependent.