Exploring structure/function relationships of cardiac ion channels: an interview with Dr. Mann and Dr. El-Ajouz
Here we meet Dr. Stefan Mann and Dr. Sam El-Ajouz, Postdoctoral Researchers at The Victor Chang Cardiac Research Institute, Sydney. Their lab is part of the Molecular Cardiology and Biophysics Division, which aims to understand both the molecular signaling pathways that operate within the heart, and the molecular basis of inherited genetic heart diseases including cardiomyopathies and arrhythmia syndromes. In this interview, Dr. Mann and Dr. El-Ajouz discuss their work, and how Cellectricon’s Dynaflow® Resolve automated perfusion system is frequently utilized to aid this research.
Cellectricon: What is the current area of research within your group?
Our lab has a strong focus on the structure/function relationships of hERG potassium channels, including the investigation of how certain drug classes cause life threatening cardiac arrhythmias when they bind to these channels. Recently we have also started to investigate structure/function relationships of bacterial and mammalian inward rectifier potassium (KIR) channels.
In terms of our research method, we complement our experimental approach with computational models of cardiac electrical activity and ion channel function. The combined data helps us to better understand the consequences of inherited and acquired changes for ion channel function on the heart and for the development of cardiac arrhythmias.
Cellectricon: What electrophysiology techniques are you using in your lab?
The scientists in our lab use a range of classical electrophysiological tools. The two most important ones for us though are:
- Whole-cell and excised-patch single electrode voltage clamp of mammalian expression systems and isolated cardiomyocytes (from various species)
- Two electrode voltage clamp from Xenopus oocytes
In addition to these conventional approaches we also use voltage clamp fluorometry to simultaneously measure current flow and conformational changes in hERG channels.
Cellectricon: What is your current key application(s) for the Dynaflow Resolve system?
We use the Resolve system mostly for studying drug binding to hERG and KIR channels. The most important advantage for us with the system is the very fast drug application time (in the order of 10s of milliseconds), which we utilize for kinetic measurements of hERG / drug interactions. Other notable benefits offered by Dynaflow Resolve, are the level of consistency, which is hard to achieve with other perfusion platforms, and the small quantity of compounds that are needed for each experiment. As a bonus, we also find that setting up an experiment is quick and easy.
Cellectricon: Our Dynaflow Resolve chip is reuseable. What have you found to be the main benefits of switching from disposable chips to the Resolve chip?
Switching over from the disposable chips has certainly reduced the cost of consumables for us. Also, it is easy to extend the running time of Resolve chips by simply topping up the wells before they run out – something that was not possible with the old, disposable system. We also find that the Resolve chip is less prone to trapping air bubbles at the channel outlets, which improves the overall stability of the assay.
The next advancement for us, and something we are eagerly awaiting, is for temperature control to become available, so that we can expand the use of Cellectricon’s Dynaflow Resolve system into other experiments.
Cellectricon: How do you see your use of the Dynaflow Resolve system developing in the future? Do you have any plans for new applications or projects?
Once the temperature control for the Resolve chips is available we intend to use the system for recording currents at physiological temperatures. At the moment though, where room temperature recordings are sufficient, the Resolve system is our go-to system for any experiment that involves drug application, due to the low cost and ease-of-use compared to traditional gravity based systems.
The Victor Chang Cardiac Research Institute is an independent, not-for-profit research facility, dedicated to the memory of cardiac surgeon Dr Victor Chang. The Institute was founded in 1994 and has grown to become a world-class cardiac research and research training facility. Dr Mann earned his PhD in 2006 from Ruhr-Universität Bochum and is currently a Senior Postdoctoral Fellow at Victor Chang Institute and conjoint lecturer at the University of New South Wales. His research focuses on inherited and acquired cardiac arrhythmias and computer simulation of cardiac electrical activity.
Dr El-Ajouz earned his PhD in 2011 from University of Leicester and is currently a Postdoctoral Researcher at Victor Chang Cardiac Research Institute. During his PhD studies he investigated the site of agonist and antagonist action at the P2X1 receptor using two-electrode voltage clamp of oocytes. In his current position at Victor Chang Institute Sam is investigating the gating of Kir channels by using site directed mutagenesis and patch clamp recordings.