ABSTRACT
Connexin hemichannels are nonselective channels that are permeable to atomic ions and small metabolites including transmitters such as ATP and glutamate. This chapter provides a short description of the advantages and the considerations for the use of Xenopus oocytes and the whole-cell two-electrode voltage clamp (TEVC) technique to examine the connexin hemichannel activity. It presents only the general considerations involved in using electrophysiological approaches in Xenopus oocytes expressing connexin channels. The whole-cell TEVC uses two microelectrodes inserted into the oocyte, rather than using one patch electrode on the surface followed by rupturing the membrane, as is done in mammalian cells. The gating and permeability properties of connexin hemichannels are highly specific and tightly regulated. An important characteristic feature of connexin hemichannels, when compared to other ion channels, is their slow gating kinetics, which are in the range of seconds and can resemble those of electrogenic membrane transporters.
