cardiac electrophysiology applications

emka TECHNOLOGIES is your supplier of software and hardware for electrophysiology studies with cardiac excitatory tissues, such as Purkinje fibre, bundle of His and papillary muscles.

Action potentials and other changes in membrane potentials are detected at a single cell level by means of a microelectrode whose tip lies inside the cell.

In common with other setups for isolated tissue study, the system must ensure a continuous supply of nutrient- and oxygen-rich perfusate at the right temperature. The specificities of this setup are related to the very small distances involved and the very weak currents generated.

The contact stimulation electrodes (or field electrodes) are linked to a software-controlled stimulator, allowing you to trigger contraction according to your protocol. Electrodes and stimulators are specially adapted to electrophysiology studies: for example, the stimulator is electrically isolated from both ground and the trigger device, further minimizing any potential interference. The stimulator can be driven by iox. Settings include: current or voltage, pulse frequency, single or dual pulse, dual pulse width….

Micromanipulators and a microscope are necessary to correctly position the microelectrode.

hardware

• • vibration-free table
• • bath incorporating micromanipulator, reference and stimulation electrodes, input and output connector for perfusate, and, optionally, a force transducer
• • microelectrode: the fine-tip electrodes are created on demand from capillary glass (either borosilicate or aluminosilicate) using a capillary glass puller
• • microscope and cold light source
• • micromanipulator: required for fine manipulation of the microelectrode

for perfusion and temperature control

• • peristaltic pump: with 2 channels, for input and output of perfusate
• • thermostatically controlled heater and temperature sensor
• • carbogen bottle

for signal conditioning

• • electrophysiology amplifier
• • interface box
• • PC with acquisition card
• • strain-gage amplifier (if force transducer used)

The bath (shown below) is more than a container; it contains channels for the passage of liquid and cables, and acts as a support structure for other parts. The tissue (not shown) is mounted between two hooks; one of the hooks is connected to a force transducer; the other is normally immobile during an experiment but its position may be adjusted via a micromanipulater integrated in the bath.

software

Data acquisition and real-time analysis are performed by iox with specific add-on analyzers offering a high level of user control.

measured parameters:

vap analyzer (ventricular action potential): resting membrane potential, maximum diastolic potential, conduction time, maximum depolarization rate, action potential amplitude, action potential overshoot, plateau voltage, action potential durations (each based on user-defined criteria), frequency, effective refractory period, recovery time, transitory rapid repolarization

nap analyzer (nodal action potential): maximum diastolic potential, threshold potential, maximum depolarization rate, action potential amplitude, action potential overshoot, action potential durations (each based on user-defined criteria), frequency

rhythmic analyzer (for contraction): base and beak of contraction, developed force, frequency, time to peak contraction, relaxation times (each based on user-defined criteria), min / max derivative, AUC

further reading

Picard S, Goineau S, Rouet R (2006) The Action Potential of the Purkinje Fiber: An In Vitro Model for Evaluation of the Proarrhythmic Potential of Cardiac and Noncardiac Drugs. Current Protocols in Pharmacology. UNIT 11.3