2018 - A Sensor Based Technique for Pharmacological Safety Testing of Cardiac Transport Proteins NCX, NaKATPase and Respiratory Chain Complexes
CardioExcyte 96 and SUFE²R 96SE poster, SPS 2018 (1.7 MB)
Ion channels have long been targets for cardiac safety testing. However, other proteins involved in the transport of ions across membrane barriers are also relevant for pharmacological safety. To drive the progress in pharmacological investigation of cardiac transporters we have evaluated new methodologies to study both desired and unwanted effects of compounds on several cardiac transport proteins, based on solid supported membrane (SSM) and impedance technologies, recording from either 1 or 96 wells simultaneously. As protein containing samples we have used HEK293 cell lines, mitochondrial inner membrane vesicles from pig heart as well as iPSC-derived cardiomyocytes on automated devices. We have focused on two transporters that emerged as targets for cardiac pharmacology and safety testing. First we investigated the Sodium-Calcium Exchanger (NCX), which plays an important role in the cellular calcium homeostasis under physiological and pathological conditions. Inhibition of NCX is thought to be beneficial in ischemia/reperfusion injury but also might have an anti-arrhythmic effect. As a second target we investigated Na+/K+-ATPase, which plays a major role in the regulation of basic cardiac functions and is targeted by cardiac glycosides, illustrating its critical involvement in both beneficial and potentially harmful pharmacological effects. Additionally, we have investigated the complexes of the respiratory chain as interference with these ATP-producing proteins can lead to lethal side effects.
We developed several new methods to investigate these cardiac transporters in 96 well formats, thus vastly increasing throughput, a critical factor in pharmacological screening. We showed dose dependent effect of known substrates and inhibitors, thus verifying the reliability of our methods. As first result we could show that inhibition of NCX increases the beat rate of iPSC derived cardiomyocytes.