Cx43 HCs have a single channel conductance of ~220 pS and open at low extracellular Ca2+ concentration ([Ca2+]e) or moderately increased intracellular Ca2+ concentration ([Ca2+]i) [27,28,29,30], extracellular alkaline pH [31], or by cytokines (e.g., tumor necrosis factor α (TNF-α) and interleukin 1-beta (IL-1β)) [32], oxidative stress [33], dephosphorylation in ischemia [34], mechanical stimulation [35,36,37] and others. Here, IL1B is linked to ischemia.