兔血管平滑肌延迟整流钾通道研究及其与克隆Kv1.5通道的电生理特性比较

本文用膜片箝全细胞技术比较了研究了单个兔肺动脉血管平滑肌细胞上延迟整流钾通道与克隆Ｋｖ１．５通道的电生理及药理学特性。将平滑肌细胞箝制在－４０ｍＶ，以１０ｍＶ的步跨阶跃去极化（０￣６０ｍＶ）可产生一系列快速上升的外向电流，几无衰减，其激活曲线的Ｖ１／２为２７．２ｍＶ。灌流液中加入１００ｍｍｏｌ／Ｌ和ＴＥＡ １ｍｍｏｌ／Ｌ ４ＡＰ，电流幅度均明显减小，细胞外Ｃａ＾２＋水平由１．５ｍｍｏｌ／Ｌ降至０．

Study on delayed rectifier K+ current of rabbit vascular smooth muscle cells and comparison with cloned Kv1.5 channel

Whole cell patch-clamp recorrding techniques were used to compare the electrophysiological properties between deayed rectifier K current of rabbit vascular smooth muscle cell(VSMC)and the cloned Kvl.5 channel.When VSMC is clamped at -40 mV,depolarizing the membrane potential at increasing steps of 10 mV could evoke a series of outward potassium cmrrents without any deactivation.The V1/2 of the activation curve was 27.2 mV.The curmnts decrease obviously after adding 100 mmol/L TEA or 1 mmol/L 4AP in the perfusate.When the concentration of extracellular Ca2 was decreased from 1.5 mmol/L to 0.5 or 0 mmol/L,the currents did not show much change,while in HBK7(cloned Kv1.5 channel cell)held at-8O mV,similar steparise depolarizaton could also produce a series of outward potassium currents without any deactivation decayed.V1/2 of the activation was 0.8 mV.4AP inhibited the cloned channel current with IC50 of 7.3 mmol/L,showing neither frequency-or use-dependence.TEA(30,100 and 300 mmol/L)reduced the current by 28.6%,37.4% and 46.3% respectively.Quinidine(0.1 and 1 mmol/L)decreased it by 29.7% and 37.4%.These results show what we have recorded in isolated rabbit vascular smooth muscle cells is the delayed rectifier potassium currents which are different in electrophysiological and pharmacological properties from those of cloned Kv1.5 channel current.Supported by the National Foundation of Outstanding Young Scientists(No.39425014)