| Panax Notoginseng, a valuable Traditional Chinese Medicine, is the dried roots of a member of Acanthopanax gracilistylus family. Panax notoginseng saponins (PNS) are the chief active constituents of Panax Notoginseng, and have been widely used for the treatment of cardiovascular diseases. In recent years, the reports about PNS-induced adverse reactions, such as drug-induced esophagitis, allergic epispasis and anaphylactic shock are coming to accumulate. In the present study, we aimed to clarify the potential cardiac toxicity and deleterious effects of PNS from the views of in vivo and in vitro. In addition, in order to reassess the safety of PNS in clinical treatment, the effect of PNS on hERG channel current was also studied according to the gudelines of International Conference of Harmonization (ICH).In the in vivo tests, PNS was administered by femoral vein injection to various groups of rats at the following doses: 0, 17, 50, 150 and 450 mg·kg-1. The time-dependent changes of heart rate (HR), mean arterial pressure (MAP), left ventricular systolic pressure (LVSP), maximal and minimal rate for left ventricular pressure rising and declining (±dp/dt) were recorded before administration, and at 1, 5, 10, 30 and 60 min after administration. The results showed that all the indices of cardiac functions were dropped dramatically, and all the animals died in 10 min following administration at the dose of 450 mg·kg-11, indicating PNS had the potential to induce significant cardiac toxicity. At the doses less than or equal to 50 mg·kg-1, there was no obvious change in the indices of cardiac functions mentioned above, the dose of 50 mg·kg-1 (i.e., seven times as great as the dose used in clinical treatment) could therefore be considered as the safe dose in clinical use.The cytotoxicity of PNS on the cardiac myocytes was evaluated by MTT assay and lactate dehydrogenase (LDH) leakage, using primary cultures of neonatal rat cardiac myocytes as a model. With the increasing concentrations of administration, significant changes in cell morphology were observed, manifested by disappearance of heart-beat of the myocytes, damage of cell membranes and cell death, etc. Obvious injuries of cardiac myocytes were induced by higher concentrations of PNS revealed by MTT assay, and all the myocytes died at the concentration of 10 mg·ml-1, the 50% inhibition concentration (IC50) was 6.08 mg·ml-1. PNS exposure resulted in significant LDH leakage from myocytes at the concentrations of 8, and 16 mg·ml-1 as compared to control.The hERG channel in transfected HEK293 cells was validated by Western Blot. The results indicated that the transfected cells with hERG channel displayed two clear protein bands in the position of 155 kDa and 135 kDa, but no identical binds were observed in the native HEK293 cells, which was consistent with the findings in the published reports. E-4031, a well-known inhibitor of the hERG channel obviously inhibited the hERG current of the transfected HEK293 cells, whereas PNS at the concentrations of 100 and 300μg/ml increased the amplitude of hERG channel current in a concentration- and time-dependent manner significantly, indicating PNS could reduce the myocardial action potential duration in the tested concentration range.
|
PDF Full Text Request