Department of Pharmacology, Faculty of Pharmacy, Anadolu University, Yunus Emre Campus, 26470, Eskisehir, Turkey.
Department of Biophysics, Faculty of Medicine, Ankara University, 06230, Ankara, Turkey.
Cardiovasc Toxicol. 2021 Apr;21(4):322-335. doi: 10.1007/s12012-020-09622-1. Epub 2021 Jan 3.
Consumption of illicit pharmaceutical products containing sibutramine has been reported to cause cardiovascular toxicity problems. This study aimed to demonstrate the toxicity profile of sibutramine, and thereby provide important implications for the development of more effective strategies in both clinical approaches and drug design studies. Action potentials (APs) were determined from freshly isolated ventricular cardiomyocytes with whole-cell configuration of current clamp as online. The maximum amplitude of APs (MAPs), the resting membrane potential (RMP), and AP duration from the repolarization phases were calculated from original records. The voltage-dependent K-channel currents (I) were recorded in the presence of external Cd and both inward and outward parts of the current were calculated, while their expression levels were determined with qPCR. The levels of intracellular free Ca and H (pH) as well as reactive oxygen species (ROS) were measured using either a ratiometric micro-spectrofluorometer or confocal microscope. The mechanical activity of isolated hearts was observed with Langendorff-perfusion system. Acute sibutramine applications (10-10 M) induced significant alterations in both MAPs and RMP as well as the repolarization phases of APs and I in a concentration-dependent manner. Sibutramine (10 μM) induced Ca-release from the sarcoplasmic reticulum under either electrical or caffeine stimulation, whereas it depressed left ventricular developed pressure with a marked decrease in the end-diastolic pressure. pH inhibition by sibutramine supports the observed negative alterations in contractility. Changes in mRNA levels of different I subunits are consistent with the acute inhibition of the repolarizing I, affecting AP parameters, and provoke the cardiotoxicity.
据报道，消费含有西布曲明的非法药物产品会导致心血管毒性问题。本研究旨在展示西布曲明的毒性特征，从而为临床方法和药物设计研究中更有效策略的发展提供重要启示。使用全细胞膜片钳电流钳的在线方法，从新鲜分离的心室肌细胞中确定动作电位 (AP)。从原始记录中计算 AP 的最大幅度 (MAPs)、静息膜电位 (RMP) 和复极化阶段的 AP 持续时间。在存在外部 Cd 的情况下记录电压依赖性 K 通道电流 (I)，计算内外电流部分，同时用 qPCR 确定其表达水平。使用比率微光谱荧光计或共聚焦显微镜测量细胞内游离 Ca 和 H (pH) 以及活性氧 (ROS) 的水平。使用 Langendorff 灌注系统观察分离心脏的机械活动。急性西布曲明应用 (10-10 M) 以浓度依赖性方式诱导 MAPs 和 RMP 以及 AP 和 I 的复极化阶段的显着变化。西布曲明 (10 μM) 在电或咖啡因刺激下诱导肌浆网 Ca 释放，而左心室发展压下降，舒张末期压明显下降，导致收缩力下降。西布曲明对 pH 的抑制支持观察到的收缩力负性变化。不同 I 亚基的 mRNA 水平的变化与复极化 I 的急性抑制一致，影响 AP 参数，并引发心脏毒性。
