Sarcoplasmic reticulum Ca2+ release channel ryanodine receptor (RyR2) plays a crucial role in aconitine-induced arrhythmias

摘要

The present study established a model of RyR2 knockdown cardiomyocytes and elucidated the role of RyR2 in aconitine-induced arrhythmia. Cardiomyocytes were obtained from hearts of neonatal Sprague–Dawlay rats. siRNAs were used to down-regulate RyR2 expression. Reduction of RyR2 expression was documented by RT-PCR, western blot, and immunofluorescence. Ca²⁺ signals were investigated by measuring the relative intracellular Ca²⁺ concentration, spontaneous Ca²⁺ oscillations, caffeine-induced Ca²⁺ release, and L-type Ca²⁺ currents. In normal cardiomyocytes, steady and periodic spontaneous Ca²⁺ oscillations were observed, and the baseline [Ca²⁺]i remained at the low level. Exposure to 3 μM aconitine increased the frequency and decreased the amplitude of Ca²⁺ oscillations; the baseline [Ca²⁺]i and the level of caffeine-induced Ca²⁺ release were increased but the L-type Ca²⁺ currents were inhibited after application of 3 μM aconitine for 5 min. In RyR2 knockdown cardiomyocytes, the steady and periodic spontaneous Ca²⁺ oscillations almost disappeared, but were re-induced by aconitine without affecting the baseline [Ca²⁺]i level; the level of caffeine-induced Ca²⁺ release was increased but L-type Ca²⁺ currents were inhibited. Alterations of RyR2 are important consequences of aconitine-stimulation and activation of RyR2 appear to have a direct relationship with aconitine-induced arrhythmias. The present study demonstrates a potential method for preventing aconitine-induced arrhythmias by inhibiting Ca²⁺ leakage through the sarcoplasmic reticulum RyR2 channel.