[Effects of calcineurin gene silencing on the remodeling of transient outward potassium current ionic channel in hypertrophic ventricular myocytes from neonatal rats]

Objective: To investigate the effects of calcineurin gene silencing on the remodeling of transient outward potassium current (Ito) ionic channel and action potential duration (APD) in phenylephrine (PE)-induced hypertrophic ventricular myocytes from neonatal rats. Methods: The ventricular myocytes of 1-day-old Sprague-Dawley rats were isolated and cultured for 48 h. RNA interference mediated by adenovirus carrying short hairpin RNA was used to knock down the gene which encodes the beta subtype of calcineurin A subunit (CnAβ) and the cells were divided into 4 groups as Ad-null group, Ad-null+ PE group, Ad-CnAβshRNA1(A1) group and A1+ PE group, and then cultured for 48 h. The gene expression of Kv4.2 was assayed by real-time reverse transcriptase-polymerase chain reaction. The protein expressions of CnAβ and Kv4.2 were assayed by Western blot test. Whole cell patch clamp technique was used to record Ito and action potential. Results: Treatment of the neonatal rat ventricular myocytes with PE induced the cell hypertrophy, up-regulated the protein expression of CnAβ, attenuated the gene and protein expressions of Kv4.2 and the Ito current density, and prolonged APD. Silencing of CnAβ in the neonatal rat ventricular myocytes using Ad-CnAβshRNA1 inhibited the aforementioned ability of PE significantly. Conclusion: CnAβ gene silencing inhibits the remodeling of transient outward potassium current ionic channel and change of APD in PE-induced hypertrophic ventricular myocytes from neonatal rats.