The cause of altered ionic homeostasis leading to cell death during ischemia and metabolic
inhibition is unclear. Hemichannels, which are precursors to gap junctions, are nonselective
ion channels that are permeable to molecules of less thanM r 1000. We show that
hemichannels open upon exposure to calcium-free solutions when they are either
heterologously overexpressed in HEK293 cells or endogenously expressed in cardiac
ventricular myocytes. In the presence of normal extracellular calcium, hemichannels open …