PO-137 Epigenetic regulation of exercise-improved LTCC and BKCa channels function in hypertension mesenteric arteries

Abstract

Objective To investigate the epigenetic mechanism of the voltage-gated L-type Ca2+ channel (LTCC) and the large-conductance Ca2+-activated K+ channel (BKCa) 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 8 weeks, patch clamp study, Ca2+ image, Western blot, qPCR, bisulfite sequencing PCR were used to detect the LTCC and BKCa channel currents, BKCa single channel gating properties, Ca2+ spark, mRNA and protein expression of LTCC α1c together with BKCa α and β1 subunits, DNA methylation level of α1c and β1 gene promoter region, miR-328 expression. In vitro experiment，miR-328 mimic and miR-328 inhibitor were transfected into cultured arterial myocytes to make miR-328 overexpressing or silencing, the mRNA and protein expression of α1c subunits were determined after 48 h transfection.
 Results 1) After 8 weeks of 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 BKCa current density of mesenteric arterial myocytes in SHR. 3) Exercise attenuated the increased single BKCa channel open Probability (Po) and the amplitude of Ca2+ spark in hypertension. 4) Exercise inhibited the upregulated mRNA and protein expression of BKCa β1 subunit in mesenteric arteries from SHR; β1 gene promoter was demethylation in hypertension, exercise increased the methylation level at β1 gene promoter of SHR. 5) The protein expression of LTCC α1c subunit was significantly increased in SHR, while decreased by exercise; the expression of miR-328 in mesenteric arteries was highly negative correlation with α1c subunit. 6) The miR-328 overexpression by transfecting miR-328 mimic decreased α1c subunit protein level significantly, while miR-328 inhibitor made α1c subunit a slight increase.
 Conclusions Regular aerobic exercise efficiently reduces blood pressure of SHR, enhances β1 gene promoter methylation, mediates miR-328 inhibiting the α1c expression at post-transcriptional level, which might be the epigenetic mechanism underlying exercise-improved LTCC and BKCa channels function in mesenteric arteries of hypertension.