Butler Larissa, Cros Caroline, Oldman Karen L, Harmer Alex R, Pointon Amy, Pollard Christopher E, Abi-Gerges Najah
*Translational Safety, Drug Safety and Metabolism and Discovery Sciences, Innovative Medicines and Early Development, AstraZeneca R&D, Macclesfield SK10 4TG, UK.
*Translational Safety, Drug Safety and Metabolism and Discovery Sciences, Innovative Medicines and Early Development, AstraZeneca R&D, Macclesfield SK10 4TG, UK
Toxicol Sci. 2015 Jun;145(2):396-406. doi: 10.1093/toxsci/kfv062. Epub 2015 Mar 29.
We sought to investigate whether drug-induced changes in contractility were affected by pacing rates that represent the range of heart rates encountered in vivo. Using the cell geometry measurement system (IonOptix), we paced dog cardiomyocytes at different cycle lengths (CLs) of 2000, 1000, 500, and 333.3 ms, before and after exposure to 13 inotropic drugs. Time course data using vehicle control (0.1% dimethyl sulfoxide (DMSO)) demonstrated stability of the system at all CLs tested. Seven positive inotropes (eg isoproterenol) exerted rate-dependent increases in sarcomere shortening (Sarc. short.; maximal effect at a CL of 333.3 ms [0.1 µM isoproterenol increased Sarc. short. by 41.1% and 145.9% at 2000 and 333.3 ms, respectively]). Omecamtiv mecarbil showed an atypical profile (increased Sarc. short. at 2000 ms [106.9%] and decreased at 333.3 ms [IC(50) = 0.64 µM]). Four negative inotropes (eg flecainide) showed rate-independent inhibition of Sarc. short. (IC(50)s: 3.3 µM [2000 ms] versus 2.3 µM [333.3 ms]). The remaining negative inotropes, verapamil, and BTS (N-benzyl-p-toluene sulphonamide) produced an increase (IC(50)s: 3.9 µM [2000 ms] versus 0.043 µM [333.3ms]) and decrease (IC(50)s: 18.3 µM [2000 ms] versus 34.0 µM [333.3 ms]) in potency, respectively. Negative inotropes (eg flecainide, BTS, and verapamil) decreased the area of the Ca(2+) transient versus Sarc. short. hysteresis loop, although rate dependency was seen with verapamil only. Positive inotropes (eg isoproterenol and levosimendan) induced a rate-dependent increase in the area, however Omecamtiv mecarbil increased and decreased the area at CLs of 2000 and 333.3 ms, respectively. Thus, the use of different pacing rates may improve the detection of inotropes in early drug discovery and illustrate the potential for finger-printing different mechanisms of action.
我们试图研究药物诱导的收缩性变化是否受代表体内所遇心率范围的起搏频率影响。我们使用细胞几何测量系统（IonOptix），在暴露于13种变力性药物之前和之后，以2000、1000、500和333.3毫秒的不同心动周期长度（CLs）对犬心肌细胞进行起搏。使用载体对照（0.1%二甲亚砜（DMSO））的时程数据表明该系统在所有测试的CLs下均稳定。七种正性肌力药物（如异丙肾上腺素）使肌节缩短（Sarc. short.）呈频率依赖性增加（在CL为333.3毫秒时效果最大[0.1微摩尔异丙肾上腺素在2000和333.3毫秒时分别使Sarc. short.增加41.1%和145.9%]）。奥米卡替麦卡比表现出非典型特征（在2000毫秒时Sarc. short.增加[106.9%]，在333.3毫秒时降低[IC(50)=0.64微摩尔]）。四种负性肌力药物（如氟卡尼）对Sarc. short.表现出频率非依赖性抑制（IC(50)：2000毫秒时为3.3微摩尔，333.3毫秒时为2.3微摩尔）。其余负性肌力药物、维拉帕米和BTS（N-苄基对甲苯磺酰胺）分别使效价增加（IC(50)：2000毫秒时为3.9微摩尔，333.3毫秒时为0.043微摩尔）和降低（IC(50)：2000毫秒时为18.3微摩尔，333.3毫秒时为34.0微摩尔）。负性肌力药物（如氟卡尼、BTS和维拉帕米）使Ca(2+)瞬变与Sarc. short.滞后环的面积减小，不过仅维拉帕米表现出频率依赖性。正性肌力药物（如异丙肾上腺素和左西孟旦）使面积呈频率依赖性增加，然而奥米卡替麦卡比在2000和333.3毫秒的CLs下分别使面积增加和减小。因此，使用不同的起搏频率可能会改善早期药物发现中对变力性药物的检测，并阐明区分不同作用机制的潜力。
