Potassium channels of myenteric neurons in guinea-pig small intestine.
Potassium channels of myenteric neurons in guinea-pig small intestine.
复制标题
豚鼠小肠肌间神经元的钾通道。
DOI：
10.1016/s0306-4522(98)00337-6
复制
发表时间：
1999
期刊：
影响因子：
3.3
通讯作者：
Wood,JD
中科院分区：
文献类型：
--
作者：
Zholos,AV;Baidan,LV;Starodub,AM;Wood,JD
采用膜片钳记录法研究短期培养时肌肠神经元的整流K+电流。在抑制Ca2+激活K+电流的条件下，通过电压激活K+电流的激活、失活、动力学和药理学特征，鉴定出3种电压激活K+电流。这些是a型电流，延迟向外整流电流（IK.dr）和内向整流电流（IK.ir）。本土知识。它由瞬时分量和随时间变化的电流组成，该电流在电位负至−80毫伏时迅速增加。激活的时间常数与电压有关，在- 80和- 100 mV之间，31 mV超极化的激活时间常数降低了e倍，从800 ms减少到145 ms。本土知识。我没有灭活。本土知识。在无K+溶液中被消除。外部K增加+ IK增加。电导率与外部K+浓度的平方根有直接关系。活化动力学加速，活化范围向更正的K+平衡电位移动。本土知识。体外Cs+和Ba2+以浓度依赖的方式抑制其生长。Ca2+和Mg2+的效果低于Ba2+IK，其不受四乙基铵离子的影响。本土知识。在−20 ~ 30 mV的膜电位范围内，dra被激活，激活时间常数从145 ms减少到16 ms，减少了5倍。在5mv时半活化，在50mv时完全活化。在2.5 s的测试脉冲中，不可见失活。本土知识。四乙基铵或4-氨基吡啶均能以浓度依赖性而非电压依赖性的方式抑制dr1，并且对Cs2+不敏感。结果表明，IK。在维持高静息膜电位方面，ir1可能是重要的。他们还建议IK的重要性。后超极化型神经元中大超极化后电位的增强以及与抑制性突触后电位相关的超极化的通道。本土知识。超极化型肠神经元具有整体动力学和电压行为，就像其他可兴奋细胞中的延迟整流电流一样，其中电流也可以与a型和Ca2+激活的K+电流区分开来。
Patch-clamp recording was used to study rectifying K+currents in myenteric neurons in short-term culture. In conditions that suppressed Ca2+-activated K+current, three kinds of voltage-activated K+currents were identified by their voltage range of activation, inactivation, kinetics and pharmacology. These were A-type current, delayed outwardly rectifying current (IK.dr) and inwardly rectifying current (IK.ir). IK.irconsisted of an instantaneous component followed by a time-dependent current that rapidly increased at potentials negative to −80 mV. Time-constant of activation was voltage-dependent with an e-fold decrease for a 31-mV hyperpolarization amounting to a decrease from 800 to 145 ms between −80 and −100 mV. IK.irdid not inactivate. IK.irwas abolished in K+-free solution. Increases in external K+increased IK.irconductance in direct relation to the square root of external K+concentration. Activation kinetics were accelerated and the activation range shifted to more positive K+equilibrium potentials. IK.irwas suppressed by external Cs+and Ba2+in a concentration-dependent manner. Ca2+and Mg2+were less effective than Ba2+IK, irwas unaffected by tetraethylammonium ions. IK.drwas activated at membrane potentials positive to −30 mV with an e-fold decrease in time-constant of activation from 145 to 16 ms between −20 and 30 mV. It was half-activated at 5 mV and fully activated at 50 mV. Inactivation was indiscernible during 2.5 s test pulses. IK.drwas suppressed in a concentration-, but not voltage-dependent manner by either tetraethylammonium or 4-aminopyridine and was insensitive to Cs2+. The results suggest that IK.irmay be important in maintaining the high resting membrane potentials found in afterhyperpolarization-type enteric neurons. They also suggest importance of IK.irchannels in augmentation of the large hyperpolarizing after-potentials in afterhyperpolarization-type neurons and the hyperpolarization associated with inhibitory postsynaptic potentials. IK.drin afterhyperpolarization-type enteric neurons has overall kinetics and voltage behaviour like delayed rectifier currents in other excitable cells where the currents can also be distinguished from A-type and Ca2+-activated K+current.