Abstract: Objective To investigate the role of large conductance calcium-activited potassium channels(BK) in the regulation of intracelullar free calcium concentration([Ca2+]i) and. excitability of mouse cortical neuron Methods Culture neuronal cells of C57BL/6 mouse cortex. Observe the influence of IBERIOTOXIN(100nmmol/L) on neuronal action potentials and [Ca2+]i with patch-clamp techniques. evoke prolonged depolarization of cultured neurons by 100pA electric current lasting 500ms, Measure the rate of firing and [Ca2+]i. Perfuse extracellular solution with KCl(20mmol/L), compare the changes of [Ca2+]i with or without IBERIOTOXIN (100nmol/L). Results No significant changes of neuronal spontaneous action potential frequency and [Ca2+]i was observed in physiological condition after perfusion of IBERIOTOXIN (n=7,P＞0.05). The frequency of action potential evoked by electric current is higher after perfusion of IBERIOTOXIN, as well as the [Ca2+]i level during depolarization(n=9,P＜0.05). Extracellular high concentration of KCl increases [Ca2+]i of neurons. When IBERIOTOXIN was applied, [Ca2+]i was much higher than without IBERIOTOXIN (n=9,P＜0.05). Conclusions BK may play an important part in the regulation of neuronal intracellular free calcium and excitability.

Key words: Large conductance calcium-activited cotassium channel, Neuron, Calcium, Membrane patch-clamp