Temperature effect on hERG channel pharmacology measured using the qube automated patch clamp system

Abstract

The human ether-à-go-go related gene (hERG) function is crucial for cardiac repolarization. Inhibition of the hERG channel can prolong cardiac action potentials, increasing the risk of ventricular arrhythmias, including torsade de pointes (TdP). Therefore, in vitro evaluations of compound effects on the hERG channel are routinely conducted in drug development to detect potential arrhythmic side-effects. Traditionally, these evaluations are performed at ambient temperatures. However, previous studies have shown that potency for certain compounds is underestimated when compared to tests at near-physiological temperatures. This study aims to highlight the importance of a temperature-controlled measuring environment for accurate evaluation of hERG channel blockers and to demonstrate the capabilities of the Qube automated patch clamp system in providing such an environment. We utilized the Qube 384 automated patch clamp system, equipped with a temperature control unit, to investigate the effects of temperature on concentration-response relationships for a panel of known hERG channel blockers. The Qube system allows for up to 384 parallel recordings at controlled temperatures ranging from 8 °C and above. Biophysical and pharmacological experiments were conducted to assess the impact of temperature on channel activation and inactivation kinetics, as well as compound potency. Our experiments showed that temperature control significantly influences hERG channel pharmacology. We observed an increased rate of activation, a leftward shift in steady-state activation, and a rightward shift in steady-state inactivation with rising temperatures. Pharmacological responses varied with different compounds; for instance, verapamil and quinidine potencies remained unchanged with temperature variations, while erythromycin, sotalol, E-4031, and cisapride exhibited pronounced leftward shifts in potency when temperature increased from 18 °C to 34 °C. The findings underscore the importance of temperature control in hERG channel evaluations. The Qube 384 automated patch clamp system, with its ability to regulate and standardize temperature at the measurement site, proves to be a reliable tool for routine compound testing under controlled temperature conditions. This study confirms that accounting for temperature is critical in accurately assessing the pharmacology of hERG channel blockers, thereby enhancing the predictive power of in vitro assays in drug development.