A patch‐clamp study of K+‐channel activity in bovine isolated tracheal smooth muscle cells
A patch‐clamp study of K+‐channel activity in bovine isolated tracheal smooth muscle cells
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牛离体气管平滑肌细胞 K+通道活性的膜片钳研究
DOI：
10.1111/j.1476-5381.1991.tb12269.x
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发表时间：
1991
影响因子：
7.3
通讯作者：
R. Small
中科院分区：
文献类型：
--
作者：
K. A. Green;R. W. Foster;R. Small
1酶消化法分离牛气管平滑肌细胞。采用膜片钳技术研究了这些细胞中大电导质膜K+通道的特性。2当[K+]对称高（140 mm）时，以及当膜胞质侧的[Ca 2 +]在标称0至10 μm范围内变化时，由内而外的质膜膜记录。观察到Ca 2+依赖型和非依赖型的大单位电流。在+20 mV和+40 mV之间测量，携带这些电流的通道的斜率电导分别为249 ± 18 pS和268 ± 14 pS。[3]将膜片胞质侧的[K+]从140 mm降低到6 mm，将两种类型的单位电流的反转电位从约0 mV移至10 mV +40 mV，表明两种电流都由K+通道携带。4在由内而外的质膜膜片中检测到的Ca 2+依赖性和非依赖性K+通道也可以根据其对应用于膜片胞质表面的抑制剂（四乙基铵（TEA），1-10 mm; Cs+，10 mm; Ba 2+，1-10 mm;奎尼丁，100 μm）的敏感性来区分。5当[K+]对称高（140 mm）时，以及当膜片胞质侧的[Ca 2 +]从标称0变化到1 μm时，从质膜外膜片进行记录。观察到Ca 2+依赖性单位电流，携带这些电流的通道的斜率电导为229 ± 5 pS。6将TEA（1 mm）、Cs+（10 mm）、Ba 2+（10 mm）或奎尼丁（100 μm）应用于贴片外表面可抑制在外向贴片中检测到的Ca 2+依赖性K+通道活性。4-氨基吡啶（4-AP; 1 mm）作为抑制剂无效。7从外向外膜片记录的Ca 2+依赖性K+通道的活性被Charybdotoxin（100 nm）可逆地抑制。8当进行全细胞记录时，施加去极化电压斜坡诱发外向电流，该外向电流依赖于记录移液管中的[Ca 2 +]，并且可以被施加到细胞外表面的Charybdotoxin（50 nm-1 μm）可逆地抑制。9我们得出结论，牛气管细胞具有丰富的Charybdotoxin敏感性、大电导、Ca 2+依赖性K+通道。这些通道携带大部分由去极化斜坡诱发的外向电流，并在确定气管细胞的外向整流特性中发挥重要作用。大的Ca 2+非依赖性K+通道的作用仍不清楚。
1 Single smooth muscle cells were isolated from bovine trachealis by enzymic digestion. The properties of large conductance plasmalemmal K+‐channels in these cells were studied by the patch‐clamp recording technique. 2 Recordings were made from inside‐out plasmalemmal patches when [K+] was symmetrically high (140 mm) and when [Ca2+] on the cytosolic side of the patch was varied from nominally zero to 10 μm. Large unitary currents of both Ca2+‐dependent and ‐independent types were observed. Measured between +20 and +40 mV, the slope conductances of the channels carrying these currents were 249 ± 18 pS and 268 ± 14 pS respectively. 3 Lowering [K+] on the cytosolic side of the patches from 140 to 6 mm, shifted the reversal potentials of the two types of unitary current from approximately zero to ≫ +40 mV, suggesting that both currents were carried by K+‐channels. 4 The Ca2+‐dependent and ‐independent K+‐channels detected in inside‐out plasmalemmal patches could also be distinguished on the basis of their sensitivity to inhibitors (tetraethylammonium (TEA), 1–10 mm; Cs+, 10 mm; Ba2+, 1–10 mm; quinidine, 100 μm) applied to the cytosolic surface of the patches. 5 Recordings were made from outside‐out plasmalemmal patches when [K+] was symmetrically high (140 mm) and when [Ca2+] on the cytosolic side of the patch was varied from nominally zero to 1 μm. Ca2+‐dependent unitary currents were observed and the slope conductance of the channel carrying these currents was 229 ± 5 pS. 6 Activity of the Ca2+‐dependent K+‐channel detected in outside‐out patches could be inhibited by application of TEA (1 mm), Cs+ (10 mm), Ba2+ (10 mm) or quinidine (100 μm) to the external surface of the patch. 4‐Aminopyridine (4‐AP; 1 mm) was ineffective as an inhibitor. 7 The activity of the Ca2+‐dependent K+‐channel recorded from outside‐out patches was reversibly inhibited by charybdotoxin (100 nm). 8 When whole‐cell recording was performed, the application of a depolarizing voltage ramp evoked outward current which was dependent on the [Ca2+] in the recording pipette and which could be reversibly inhibited by charybdotoxin (50 nm–1 μm) applied to the external surface of the cell. 9 We conclude that bovine trachealis cells are richly endowed with charybdotoxin‐sensitive, large conductance, Ca2+‐dependent K+‐channels. These channels carry most of the outward current evoked by a depolarizing ramp and could play a major role in determining the outward rectifying properties of the trachealis cells. The role of the large Ca2+‐independent K+‐channels remains unclear.
Charybdotoxin 的纯化，一种高电导 Ca2 激活 K 通道的特异性抑制剂。
DOI：
--
发表时间：
1986
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Smith,C;Phillips,M;Miller,C
通讯作者：
Miller,C
影响因子：
56.9
作者：
STANDEN, NB;QUAYLE, JM;NELSON, MT
通讯作者：
NELSON, MT