Evaluation of cardiac safety of hydroxyrutaecarpine, hERG channel inhibitor / 药学学报

Drug-induced long QT syndrome (LQTS) has become an important clinical research topic, and the occurrence of acquired long QT syndrome (acLQTS) is mainly caused by drug inhibition of the human ether-α-go-go related gene (hERG) channel. The hERG gene encodes the α subunit of the fast-activating delayed rectifying potassium ion channel (Ikr), which plays an important role in the process of action potential phase 3 repolarization and is also the target of most antiarrhythmic drugs. The purpose of this study was to investigate the effect of hydroxyrutaecarpine (HRU) on the hERG channel and to evaluate its cardiotoxicity. The whole cell patch clamp technique was used to detect the effects of HRU on the current and kinetics of the hERG channel, and to confirm the binding site on the hERG channel. PCR was used to determine the effect of HRU on hERG mRNA expression. Western blotting was used to detect the effects of HRU on the expression of hERG protein and transcription factor Sp1. Immunofluorescence was used to confirm the effects of HRU on localization and expression of hERG protein and transcription factor Sp1. Studies have shown that transient HRU can inhibit hERG current and shorten the inactivation time constant. Its binding sites to the hERG channel are F656 and Y652. After incubation for 24 h, HRU can reduce the expression of hERG protein, inhibit the hERG current, reduce the level of hERG mRNA, and reduce the expression of transcription factor Sp1 in the nucleus and hERG protein in the cytoplasm. Immunofluorescence experiments also showed the same results suggesting that the inhibition of Sp1 expression by HRU is the cause of the decreased expression of hERG mRNA. In conclusion, the acute inhibition of HRU accelerates the channel inactivation process and reduces the inactivation time constant by binding to the F656 and Y652 sites in the hERG channel, thus reducing the hERG current. In addition, HRU also inhibits the expression of hERG protein, mainly by inhibiting the expression of transcription factor Sp1, the transcription function of hERG channel protein is down-regulated, so that the hERG protein is reduced.

Cardiac safety evaluation of berberine combining with berberine-derived medicine / 药学学报

Drug-induced cardiotoxicity is a serious concern in recent years, and acquired long QT syndrome (LQTS) is an important manifestation of cardiotoxicity. hERG gene encodes the α subunit of the rapidly activated delayed rectifier potassium channel (Ikr), which plays an important role in action potential phase 3 repolarization. Drug inhibition of Ikr/hERG channel leads to prolonged QT interval, accompanied by Tdp malignant arrhythmia, which can cause sudden death. We studied the effect of berberines on the hERG K+ channels after combination with rosuvastatin and glibenclamide, and evaluated the cardiac safety of these drugs in combination. Whole cell patch clamp technique was used to detect the effect of the combinations of these drugs on hERG current on HEK293 cells stably expressing hERG gene. The results showed that the inhibitory effects of berberine or dihydroberberberine combined with rosuvastatin on hERG current were higher than single drug (P<0.05), but the combination had no effect on the kinetics of hERG channel. Berberine or dihydroberberberine combined with glibenclamide had higher inhibitory effects on hERG current than the application of single drug (P<0.05) while the time constant of hERG channel inactivation was shortened after the combination (P<0.05). In addition, the combination of berberine and glibenclamide inhibited hERG channel activation (P<0.05). In conclusion, our results demonstrated that the combination of berberine with rosuvastatin or glibenclamide significantly inhibited hERG current and the inhibition effects were higher than the application alone. Therefore, when the two drugs that have inhibitory effects on the hERG channel are combined, the risk of inducing prolonged QT interval is significantly increased, and therefore reducing cardiac safety.

Discussions on the development of biomechanics based on applications and grants of NSFC / 医用生物力学

Biomechanics, one important sub-discipline of mechanics, is an interdisciplinary subject involved in mechanics, biology and medical science, and it is closely associated with life health and clinic medicine. In this paper, applications and grants of normal projects and youth science foundation projects of National Natural Science Foundation of China (NSFC) on biomechanics from year 2012 to 2016 are introduced. Research directions and research teams of biomechanics are mainly discussed, and some suggestions are given for the development of biomechanics in China.