EVA 8

A typical application is the investigation of exocytosis processes, e.g. secretion of transmitters or hormones, and the measurement of extracellular concentrations of neurotransmitters (e.g. dopamine, noradrenaline, serotonin).

The internal design of the EVA 8 is based on the well proven EPC 8 Patch Clamp Amplifier and provides the same high hardware quality and similar features. Technically, the EVA 8 is noteworthy for three special features:

• range-changing capability of the head stage
• extremely wide bandwidth available from the current monitor circuitry
• the computer control possibility

Together these features allow that a single head stage suffices for use with the different size of electrodes to allow a wide range of current measurement. The versatility of the EVA 8 can best be appreciated by the variety of experiments that can be carried out with them. Besides high resolution recordings of ion concentration this unit can be used in studies of quantitative determination of organic and inorganic compounds, determination of electron transfer and reaction mechanism, studies of oxidation and reduction process.

A positive electrode potential guarantees oxidation of the transmitter by the electrode. While the potential is kept constant, an increase of the local transmitter concentration induces a small increase of the measured outward current. This outward current is caused by the release of electrons from the transmitter to the carbon fiber electrode. The time resolution of this method is usually below 1 ms. It can be used to detect the release of single vesicles from secreting cells.

Features

• Manual or Computer Controlled
• Capacitance Compensation
• Current sensitivity: 5 mV/nA to 1 V/pA
• ± 2 Volt Command Ranges
• 17 Current Output Gain Ranges
• 7 Pole Bessel Filter adjustable from 0.1 - 30 kHz in 11 steps
• Two External Command Ranges for 1 Volt or 2 Volt at the headstage
• Three gain ranges
• Largest measurable currents:
  200 pA (50 GΩ, range)
  20 nA (500 MΩ, range)
  2 µA (5 MΩ, range)