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

Abstract

The present study established a model of RyR 2 knockdown cardiomyocytes and elucidated the role of RyR 2 in aconitine-induced arrhythmia. Cardiomyocytes were obtained from hearts of neonatal Sprague-Dawlay rats. siRNAs were used to down-regulate RyR 2 expression. Reduction of RyR 2 expression was documented by RT-PCR, western blot, and immunofluorescence. Ca 2+ signals were investigated by measuring the relative intracellular Ca 2+ concentration, spontaneous Ca 2+ oscillations, caffeine-induced Ca 2+ release, and L-type Ca 2+ currents. In normal cardiomyocytes, steady and periodic spontaneous Ca 2+ oscillations were observed, and the baseline [Ca 2+ ] i remained at the low level. Exposure to 3 μM aconitine increased the frequency and decreased the amplitude of Ca 2+ oscillations; the baseline [Ca 2+ ] i and the level of caffeineinduced Ca 2+ release were increased but the L-type Ca 2+ currents were inhibited after application of 3 μM aconitine for 5 min. In RyR 2 knockdown cardiomyocytes, the steady and periodic spontaneous Ca 2+ oscillations almost disappeared, but were re-induced by aconitine without affecting the baseline [Ca 2+ ] i level; the level of caffeine-induced Ca 2+ release was increased but L-type Ca 2+ currents were inhibited. Alterations of RyR 2 are important consequences of aconitinestimulation and activation of RyR 2 appear to have a direct relationship with aconitine-induced arrhythmias. The present study demonstrates a potential method for preventing aconitine-induced arrhythmias by inhibiting Ca 2+ leakage through the sarcoplasmic reticulum RyR 2 channel.

Activation of cardiac M3 muscarinic acetylcholine receptors has cardioprotective effects against ischaemia‐induced arrhythmias

“…The Ca 2+ release channels (ryanodine receptors; RyRs) of the sarcoplasmic reticulum play a fundamental role in cardiac [Ca 2+ ] i overload . In the present study, to investigate whether the inhibitory effect of choline on [Ca 2+ ] i overload is mediated by RyRs, we exposed cells to 10 mmol/L caffeine, an RyR agonist.…”

Arrhythmogenesis Toxicity of Aconitine Is Related to Intracellular Ca2+ Signals

“…It was reported that arrhythmias induced by aconitine had a direct relationship with the activation of RyR 2 by disrupting intracellular Ca 2+ homeostasis 17. However, in neonatal rat ventricular myocytes, aconitine decreased the density of I Ca-L 18. The inhibition of I Ca-L resulting in retrograde communication between the SR Ca 2+ release channel and I Ca-L and the direct effect of aconitine on I Ca-L are unclear.…”

L-Type Calcium Channel Inhibition Contributes to the Proarrhythmic Effects of Aconitine in Human Cardiomyocytes

“…In addition, ACO-induced L-type Calcium channel (LTCC) inhibition has been observed in neonatal [11] and isolated adult [12] rat cardiac myocytes. Accumulated intracellular Na + has been recognized for activating the reverse-mode of Na + -Ca 2+ exchanger (NCX) and increasing cytosolic [Ca 2+ ] i , which can trigger intercellular [Ca 2+ ] i concentration dependent inactivation (CDI) of the LTCC [13,14].…”