ALA Scientific Xenoplace Workstation

The ALA Scientific Xenoplace Workstation is a compact, two-electrode voltage clamp system built around high-end components. It can be configured for specialised applications such as electrophysiology; extracellular, in vitro and in vivo recordings; and investigating the electrical properties of Xenopus oocytes (the egg of the African leopard frog).

Oocytes are useful in electrophysiology and pharmacology research because the pre-emergent egg is basically a factory ready to make a frog, and therefore able to process a wide variety of RNA. As such, it is capable of processing the RNA that codes for membrane ion channels and can easily express those channels in the membrane of the egg. Since a typical egg is about 1 mm across, millions to billions of channels can be expressed, giving rise to large currents that can be more easily studied than in a neuron or other excitable tissue.

The large size of the egg can give rise to other electrical problems that must be dealt with, such as large capacitance and high current. An amplifier such as the TEC 03 from npi is suitable to use with the Xenoplace since it contains many of the features necessary to discriminate membrane currents and give correct recordings.

The typical workstation set-up consists of the amplifier and two MM-33 manipulators mounted on a base plate. The two manipulators are positioned so that electrodes can descend into a chamber to pierce an oocyte, which can also be perfused easily with drugs or other substances. The system provides two manipulators, one for the measuring electrode and one for the current injecting electrode. There is a channel with a dimple to hold the oocyte, and two reference electrodes (AgCl pellets) are positioned adjacent to the dimple. Convenient plug-in connections allow the user to connect the reference electrodes to the head stage.

Perfusion liquid entering the chamber is channelled directly at the oocyte. Fluid is removed via a suction port from just behind the oocyte, or from a Luer connection on the side of the chamber block. There is a pedestal catch basin that supports the chamber and serves to catch the liquid if the removal system should fail. A clip holds the current injecting head stage for convenience. All the components are tied to a common base plate for convenience and stability.