Effect Of Exercise Training On The Biophysical Property Of BK_Ca Channel Of Smooth Muscle Cell In Rat Thoracic Aortic

There are four types of potassium channels in vascular smooth muscle cells (VSMC), including BK_Ca, Kv, Kir, K_ATP. Large-conductance calcium-activated potassium channels (BK_Ca) are widely expressed in VSMC, Which have the important functions in regulation of membrane potential and vascular smooth muscle tone. And more evidence proved that abnormal expression and dysfunction of BK_Ca channels are closely related to the cardiovascular diseases. The purpose of the present study was to investigate the biophysical property of BK_Ca channel of VSMC from exercised rats by using patch clamp technique.Female infancy Sprague-Dawley(SD) rats were selected as experimental animals. Swimming was taken as exhaustive training method. Groups of exhaustive training Rat were made to swim in water tanks twice daily for 90 minutes 7 days a week for 4 weeks. Before the swimming exercise, the rat practiced swimming for 8 days. The first day of swimming practice consisted of two 10-minute sessions separated by at least 4 hours. Sessions were then increased by 10 minutes each day until they reached the 90-minute target. Using enzymatic isolation method, we get a number of primary thoracic aortic smooth muscle cells of SD rats for patch clamp technique. Channel activity was studied by using the patch clamp techniques in inside-out recording.The results are following:1. There is no change in open probability of BK_Ca channel after one week exercise training. However, the results show that the open probability increased after 2 weeks and obviously increased after 3,4weeks exercise training.2. Exercise training do not change the single-channel conductance of the BK_Ca channel.These results suggest that the biophysical property of BK_Ca channel in vascular smooth muscle have been changed by exercise trainging and suggesting that the biophysical property of BK_Ca channel had great changes at pre-hypertension.