Inhibitory effects of aloperine on voltage-gated Na+ channels in rat ventricular myocytes

Inhibitory effect of aloperine on transient outward potassium currents in rat cardiac myocytes

Objective

Aloperine (ALO) is an effective quinolizidine alkaloid. Previous research has demonstrated its antiarrhythmic effect by inhibiting voltage-gated sodium currents in rat ventricular myocytes. This study explored its effect on transient outward potassium currents (Ito) in rat atrial myocytes to identify potential targets in the context of ion channel currents.

Methods

The Ito characteristics in rat atrial myocytes were recorded using a whole-cell patch-clamp technique. Molecular docking was performed to validate ligand-protein binding interactions.

Results

ALO at concentrations of 3 and 10 μM significantly reduced Ito current densities. Gating kinetics analysis revealed ALO's ability to slow Ito activation, hasten inactivation, and prolong transition from inactive to resting state. Molecular docking revealed that ALO could stably bind to KCND2.

Conclusion

ALO may inhibit Ito by slowing the activation process, accelerating inactivation, and delaying the recovery time after inactivation, potentially preventing acetylcholine-induced AF.

Aloperine targets lysosomes to inhibit late autophagy and induces cell death through apoptosis and paraptosis in glioblastoma

Glioblastoma (GBM) is an aggressive intracranial tumour, and current chemotherapy regimens have limited efficacy. Aloperine (ALO), a natural alkaline compound, has shown potential as an antitumor agent. However, the effect of ALO against GBM remains unclear. This study aimed to investigate the function of ALO in treating GBM. U87, A172, and GL261 cell lines were used for in vitro experiments, and GL261 was also used to establish in vivo models. The results showed that ALO inhibited the proliferation of GBM cells by cell cycle arrest and apoptosis. Furthermore, autophagy was found to play a critical role, suggested by observation of autophagosomes under the transmission electron microscopy. It was discovered for the first time that ALO targeted lysosomes directly in glioma cells, tested by fluo-rescence-labelled ALO and organelle-localizing probes. In addition, ALO inhibited late autophagy and induced paraptosis in GBM, verified by classical gene expression changes in qPCR and western blotting. Also, ALO inhibited tumour growth and acted synergistically with temozolomide in intracranial glioma mice models in vivo. Our findings suggest that ALO targets lysosomes to inhibit late autophagy in GBM, inducing cell cycle arrest, paraptosis, and apoptosis. ALO may therefore be a promising therapeutic agent for the treatment of GBM.

Inhibitory Effects of Nobiletin on Voltage-Gated Na+ Channel in Rat Ventricular Myocytes Based on Electrophysiological Analysis and Molecular Docking Method

Nobiletin (NOB) has attracted much attention owing to its outstanding bioactivities. This study aimed to investigate its anti-arrhythmic effect through electrophysiological and molecular docking studies. We assessed the anti-arrhythmic effects of NOB using aconitine-induced ventricular arrhythmia in a rat model and the electrophysiological effects of NOB on rat cardiomyocytes utilizing whole-cell patch-clamp techniques. Moreover, we investigated the binding characters of NOB with rNav1.5, rNav1.5/QQQ, and hNa_V1.5 via docking analysis, comparing them with amiodarone and aconitine. NOB pretreatment delayed susceptibility to ventricular premature and ventricular tachycardia and decreased the incidence of fatal ventricular fibrillation. Whole-cell patch-clamp assays demonstrated that the peak current density of the voltage-gated Na⁺ channel current was reversibly reduced by NOB in a concentration-dependent manner. The steady-state activation and recovery curves were shifted in the positive direction along the voltage axis, and the steady-state inactivation curve was shifted in the negative direction along the voltage axis, as shown by gating kinetics. The molecular docking study showed NOB formed a π-π stacking interaction with rNav1.5 and rNav1.5/QQQ upon Phe-1762, which is the homolog to Phe-1760 in hNa_V1.5 and plays an important role in antiarrhythmic action This study reveals that NOB may act as a class I sodium channel anti-arrhythmia agent.