Cartoon representing some of the agents/conditions that open/close hemichannels and an electrophysiological recording of their activity. The arrows in the diagram show the different conditions that open hemichannels, such as positive voltages (+Vm), metabolic inhibition (MI) and changes in redox potential (dithio-treitol, DTT), and the conditions that close hemichannels, such as low pH and high extracellular calcium (high Ca2+). An example of an electrophysiological recording obtained in Hela cells transfected with Cx43-EGFP in whole cell patch, voltage clamp at +30 mV, is shown under metabolic inhibition conditions as described (Contreras et al. 2002)