Effects of aerobic exercise training on large-conductance Ca(2+)-activated K (+) channels in rat cerebral artery smooth muscle cells.

PURPOSE: Large-conductance Ca(2+)-activated K(+) (BKCa) 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 BKCa 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 BKCa 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 BKCa channel activity in cerebral arterial myocytes by changing its biophysical properties, and the electrical remolding induced by exercise may be training volume-dependent.