Aconitine is an effective ingredient in Aconite tuber, an important traditional Chinese medicine. Aconitine is also known to be a highly toxic diterpenoid alkaloid with arrhythmogenic effects. In the present study, we have characterized the properties of arrhythmic cytotoxicity and explored the possible mechanisms of aconitine-induced cardiomyocytes. Results show that aconitine induces significant abnormity in the spontaneous beating rate, amplitude of spontaneous oscillations and the relative intracellular Ca2+ concentration. Also, mRNA transcription levels and protein expressions of SR Ca2+ release channel RyR(2) and sarcolemmal NCX were elevated in aconitine-induced cardiornyocytes. However, co-treatment with ruthenium red (RR), a RyR channel inhibitor, could reverse the aconitine-induced abnormity in intracellular Ca2+ signals. These results demonstrate that disruption of intracellular Ca2+ homeostasis in the cardiac excitation-contraction coupling (EC coupling) is a crucial mechanism of arrhythmic cytotoxicity in aconitine-induced cardiomyocytes. Moreover, certain inhibitors appear to play an important role in the detoxification of aconitine-induced Ca2+-dependent arrhythmias. (c) 2007 Elsevier Inc. All rights reserved.