摘要
采用膜片钳技术，在细胞贴附方式下确定并分析了昆明白小鼠腹腔巨噬细胞电压依赖的内向整流型Ｋ＋通道（Ｋｉｒ）及其基本特性。当电极液含１４５ｍｍｏｌ／ＬＫ＋，保持电位Ｖｐ在－３０ｍＶ以上时，该通道电流发放，电导为４３ｐＳ。改变［Ｋ＋］ｏ，通道外延的反转电位Ｅｒｅｖ接近于封接膜片两侧的Ｋ＋平衡电位Ｅｋ，单通道电导正比于［Ｋ＋］ｏ的平方根，但不同［Ｋ＋］ｏ下，激活通道所需驱动电位ＶＤ相同。单通道显示电压敏感性，具有长短两个开放状态和两个关闭状态。除膜电位外，［Ｋ＋］ｏ是此型通道的另一个门控因素，且在膜电位超极化增高的情况下，其作用更加显著。以粒细胞／巨噬细胞集落刺激因子ＧＭ－ＣＳＦ（１６ｎｇ／ｍｌ）预浴细胞４８小时，该通道开放概率Ｏ．Ｐ．显著升高，通道激活所需驱动电位的阈值显著下降，通道活动更加频繁。
In this study, the patch - clamp technique was used to characterize the voltage-dependent inwardly rectifying K+ channel (Kir) in the 4 - to 6 week - old kunming bai murine peritoneal exudate macrophages (PEMs). Inward single - channel currents with conductance of 43ps were observed in cell --attached patches at pipette potentials above 30 mV when the pipette contained 145 mmol/ L K+ ([K+] o). With different K+concentrations in pipette, the extrapolated reversal potentials of the currents correspondingly approached the K+ equilibrium potentials of the sealed patches, the conductance of the single - channel was proportional to the square root of [K+] o, but the driving potentials for channel activation were the same at various [K+] o. The single channel manifested voltage - sensitive kinetics, with two open and two closed states. In addition to the membrane potential, the [K+] o was another channel - gating factor and its effect was more significant especially under greater membrane hyperpolarization. If the PEMs were preincubated with GM - CSF(16ng/ml) for 48 hours, the Kir activity was increased with reduced closed time constant 2 (τc2), higher open probability, and lower threshold driving potential for Kir activation.
出处
《生物物理学报》
CAS
CSCD
北大核心
1996年第4期578-584,共7页
Acta Biophysica Sinica
