下丘脑神经元钙激活钾通道的整流现象

RECTIFICATION OF CALCIUM-ACTIVATED POTASSIUM CHANNELS IN HYPOTHALAMIC NEURONS

目的 :研究SD乳鼠下丘脑神经元中钙激活钾通道的整流现象。方法 :采用膜片钳内面向外式记录方式。结果 :记录到一种大电导钙激活钾通道 (KCa) ,在对称 140mmol/L [K+ ]时内向电导为 (171± 12 )pS ,不随 [Ca2 + ]变化而改变 ,而外向电导可受 [Ca2 + ]调控 ,当 [Ca2 + ]为 5 0 0 μmol/L时 ,外向电导为 (76± 14)pS。 [Ca2 + ]越大 ,整流现象越明显 ,Mg2 + 对这种KCa的整流作用不明显。结论 :下丘脑神经元中KCa具有Ca2 + 依赖性整流现象 。

Aim: To study the rectification of calcium activated potassium channel in hypothalamic neurons. Methods: Channels in inside out patches are studied by patch clamp technique. Results: A big conductance calcium activated K + channel was observed,with symmetrical 140mol/L across patches,in ward conductance was (171±12) pS and change little as different [Ca 2+ ] was included in the bath solution.Outward conductance was regulated by and was (76±14)pS with 500 μmol/L [Ca 2+ ].The higher level of [Ca 2+ ] caused larger degree of rectification.Mg 2+ only had a minor effect on rectification of this calcium activated K + channel. Conclusion: BK in hypothalamic neurons had rectification properties,it might play a role in neuronal excitation and stability.