Epigenetic down-regulation of BKCa channel by miR-181a contributes to the fetal and neonatal nicotine-mediated exaggerated coronary vascular tone in adult life.

BACKGROUND

Fetal origin of adult cardiovascular disease is one of the most pressing public concerns and economic problem in modern life. Maternal cigarette smoking/nicotine abuse increases the risk of cardiovascular disease in offspring. However, the underlying mechanisms and theranostics remain unclear. We hypothesized that fetal and neonatal nicotine exposure enhances microRNA-181a (miR-181a) which targets large-conductance Ca2+-activated K+ (BKCa) channels, resulting in increased coronary vascular tone in adult offspring.

METHODS

Nicotine or saline was administered to pregnant rats via subcutaneous osmotic minipumps from gestational day 4 until postnatal day 10. Experiments were conducted in adult (~6 month old) male offspring.

RESULTS

Nicotine enhanced pressure-induced coronary vascular tone, which was abrogated by BKCa channel blocker. Nicotine selectively attenuated coronary BKCa β1 but not α subunit expression. Functionally, nicotine suppressed BKCa current density and inhibited BKCa activator NS1619-induced coronary relaxations. Furthermore, activation of BKCa increased coronary flow and improved heart ischemia/reperfusion-induced infarction. Nicotine selectively enhanced miR-181a expression. MiR-181a mimic inhibited BKCa β1 expression/channel current and decreased NS1619-induced coronary relaxation. Antioxidant eliminated the difference of BKCa current density between the saline and nicotine-treated groups and partially restored NS1619-induced relaxation in nicotine group. MiR-181a antisense decreased vascular tone and eliminated the differences between nicotine exposed and control groups.

CONCLUSION

Fetal and neonatal nicotine exposure-mediated miR-181a overexpression plays an important role in nicotine-enhanced coronary vascular tone via epigenetic down-regulation of BKca channel mechanism, which provides a potentially novel therapeutic molecular target of miR-181a/BKca channels for the treatment of coronary heart ischemic disease.