Epigenetic Regulation of Exercise-improved LTCC and BK_Ca Channels Function in Hypertension Mesenteric Arteries

Objective:To investigate the epigenetic mechanism of the voltage-gated L-type Ca²⁺channel (LTCC) and the large-conductance Ca²⁺-activated K⁺channel (BK_Ca) function in mesenteric arterial myocytes improved by regular aerobic exercise in hypertension.Methods:12-week-old male SHR and WKY rats were randomly assigned to sedentary and exercise training groups, respectively.Exercise groups were performed a moderate-intensity treadmill running.After 12 weeks, patch clamp study, Ca²⁺image, Western blot, qPCR, bisulfite sequencing PCR were used to detect the LTCC and BK_Ca channel currents, BK_Ca single channel gating properties, Ca²⁺spark, m RNA and protein expression of LTCCα_1c together with BK_Caαandβ1 subunits, DNA methylation levels ofα_1c andβ1gene promoter region, miR-328 expression.In vitro experiment, miR-328 mimic and miR-328inhibitor were transfected into cultured arterial myocytes to make miR-328 overexpressing or silencing, the mRNA and protein levels ofα_1c subunits were determined after 48 h transfection.Results:1) After aerobic exercise, SBP in both exercise groups of WKY and SHR were significantly lower than that of their sedentary counterparts.2) Exercise normalized the increased LTCC and BK_Ca current density of mesenteric arterial myocytes in SHR.3) Exercise attenuated the increased single BK_Ca channel open probability (Po) and the amplitude of Ca²⁺spark in hypertension.4) Exercise inhibited the upregulated m RNA and protein expression of BK_Caβ1 subunit in mesenteric arteries from SHR;β1 gene promoterwas demethylation in hypertension, exercise increased the methylation level atβ1 gene promoter of SHR.5) The protein expression of LTCCα_1c subunit was significantly increased in SHR, while decreased by exercise;the expression of miR-328 in mesenteric arteries was highly negative correlation withα_1c subunit.6) The miR-328 overexpression by transfecting miR-328 mimic decreasedα_1c subunit protein level significantly, while miR-328 inhibitor madeα_1c subunit a slight increase.Conclusions:Regular aerobic exercise efficiently reduces blood pressure of SHR, enhancesβ1 gene promoter methylation, mediates miR-328 inhibiting theα_1c expression at post-transcriptional level, which might be the epigenetic mechanism underlying exercise-improved BK_Ca and LTCC channels function in mesenteric arteries of hypertension.