Electrophysiology is the study of the electrical properties of biological cells and tissues. It involves measurements of voltage change or electrical current flow on a wide variety of scales from single ion channel proteins to whole tissues like the heart. In neuroscience, it includes measurements of the electrical activity of neurons, and particularly action potential activity.
Ion channels play a critical role in biology. With electrophysiological techniques, researchers can study their function by measuring the flow of ions in cells and tissues, contributing to a better understanding of the underlying processes involved in normal and disease states. There are numerous approaches available to researchers interested in electrophsysiology-from low-throughput conventional methods to high-throughput, automated systems.
Voltage clamp allows researchers to "clamp" the cell potential at a chosen value to measure how much current crosses a cell's membrane at any given voltage. This is important because many ion channels are voltage-gated, and open only when membrane voltage is within a certain range.
Current clamp records membrane potential by injecting current into a cell. Unlike voltage clamp, the membrane potential is free to vary, and the amplifier records whatever voltage the cell generates on its own or as a result of stimulation. This technique is used to study how a cell responds to changes in electrical current or the presence of other molecules.
Patch clamp involves placing a microelectrode next to a cell and applying gentle suction to draw a piece of the cell membrane, or "patch," into the tip (cell-attached mode). If more suction is applied, the "patch" can be displaced, leaving the electrode sealed to the rest of the cell (whole-cell mode).
Planar (parallel) patch clamp enables high-throughput electrophysiology. A cell suspension is pipetted on a chip containing a microstructured aperture. A single cell is positioned on the aperture by suction and a tight connection (i.e., Gigaseal) is formed. This approach allows for integration of microfluidics which enables automatic compound addition to support ion channel screening.
Molecular Devices is a leader in the development of conventional electrophysiology equipment, instruments, software and automated electrophysiology systems. Please use the links below to learn more.
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