Abstract
Aconitine, a strong poisonous type of alkaloid, has a pharmaceutical effect in stimulating the membranes of cardiomyocyte. However, other effects of aconitine on the Connexin43 (Cx43) and PKCα expression on cardiomyocyte are unknown. In this study, we investigated whether aconitine also mediates the phosphorylation status of Cx43 and PKCα in cultured ventricular myocytes of neonatal rats. The band intensity of phosphorylated Cx43 and nonphosphorylated Cx43 in cultured and aconitine-treated cardiomyocytes were determined by Western blot analysis. The changes in phosphorylation status occurring in PKCα in cultures were revealed by quantitative immunofluorescent microscopy. A decreased band intensity (0.37±0.04) of phosphorylated Cx43 (P-Cx43) and a concomitant increased band intensity (3.56 ± 0.65) of nonphosphorylated Cx43 (NP-Cx43) were found, compared to the controls (1.00 for P-Cx43 and NP-Cx43). It also revealed that, after aconitine treatment, the amount of phosphorylated PKCα (P-PKCα) decreased significantly. Similar changes were revealed in phosphorylation status occurring in PKCα in the cultures under the same treatment conditions. These observations suggest that aconitine not only induces dephosphorylation of Cx43, but also alters expression of P-PKCα in cultured cardiomyocytes. Key words: Aconitine, cardiomyocyte, connexin 43 (Cx43), protein kinase C-α (PKCα), protein phosphorylation.
Highlights
Aconitium plants are typical series of officinal toxic traditional Chinese drug
Such previous conclusions based on aconitine-induced abnormal electrical activity in vivo and in vitro by clamp method (Amran et al, 2004); the involvement of the isolated single cell plays an insignificant role in the aconitine-induced arrhythmias due to syncytial structure and function of cardiomyocytes
We investigated the effects of aconitine on Cx43 phosphorylation status and protein kinase C- (PKC) in cultured ventricular myocytes of neonatal rats
Summary
Aconitium plants are typical series of officinal toxic traditional Chinese drug. Aconitine, the main effective constituent of Aconitium plants, is of effects such as cardiotonic, analgesia, anti-inflammatory, anti-tumor and so on, which contribute to widespread use in clinical (Baselt, 2004). Aconitine suppresses the deactivation of voltage-gated sodium channels, which prevents complete repolarization of the excitable membrane of cardiac tissues (Liu et al, 2008; Wang et al, 2003; Moric, et al, 2003; Li et al, 2007), all which caused aconitine-induced arrhythmias. Such previous conclusions based on aconitine-induced abnormal electrical activity in vivo and in vitro by clamp method (Amran et al., 2004); the involvement of the isolated single cell plays an insignificant role in the aconitine-induced arrhythmias due to syncytial structure and function of cardiomyocytes. Serine residues of Cx43 (Ser368) is the most important phosphorylated modification site in the cardiovascular system and it is closely related to deletion of myocardium electrical coupling and poor contraction induced by ischemia and hypoxia (Dhein et al, 2002; Schulz and Heusch, 2004; Lin et al, 2006)
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