[Kinetics of the Ca(2+)-activated K+ channel in Ca2+ induced cortex neurons damage]

Ca(2+)-activated K+ channels were studied by using the patch clamp technique of single channel recordings from the primary culture fetal SD rat cortex neurons. Besides their physiologic characters, the effects of increasing cytosolic and cytoplasmic Ca2+ triggered neuronal damage were also studied. The results showed that Kca with conductance around 170PS was predominant in the rat cortex neurons. These channels almost did not open at physiologic intracellular free Ca2+ concentration (10(-8) mol/L), but was extremely activated at intracellular free Ca2+ concentration (10(-6) mol/L). So the open probabilities of the KCa in the cortex neurons obviously depended on the concentration of cytoplasmic Ca2+ and membrane potential. The KCa activated by increasing of intracellular Ca2+ during the early stage of anoxia may be a protective reaction of ischemic neurons.