A SMALL-CONDUCTANCE CL- CHANNEL IN THE MOUSE THICK ASCENDING LIMB THAT IS ACTIVATED BY ATP AND PROTEIN-KINASE A
A SMALL-CONDUCTANCE CL- CHANNEL IN THE MOUSE THICK ASCENDING LIMB THAT IS ACTIVATED BY ATP AND PROTEIN-KINASE A
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DOI：
10.1113/jphysiol.1995.sp020715
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发表时间：
1995-05-15
影响因子：
5.5
通讯作者：
TEULON, J
中科院分区：
文献类型：
--
作者：
GUINAMARD, R;CHRAIBI, A;TEULON, J
1.用膜片钳技术在离体小鼠肾单位皮质粗升支（CTALs）基底外侧膜上发现氯离子通道。当CTAL片段与10 μ mol l（-1）毛喉素预孵育至少15分钟时，在21%的细胞附着斑中检测到电导为45 pS的通道，先前显示为Cl-选择性的。在未受刺激的CTAL小管中，在42.8%的细胞贴附斑和57%的由内而外斑中发现了另一个电导较小（7-9 pS）的通道，但在毛喉素处理的小管中，在82-87%的斑中发现了另一个电导较小的通道。小通道具有Cl-选择性（Cl-/Na+渗透率比，P-Cl/P-Na = 9.8），其渗透率顺序为：NO3- > Br- > Cl- > F- >葡萄糖酸盐。在负电压下，通道活性降低（Br-）或消失（NO3-）。在140 mmol l（-1）时，I-在所有电压下完全抑制通道活性，但使用低浓度（10 mmol l（-1））估计P-I/P-Cl比率为1.6。内部三磷酸腺苷（ATP）增加了48%的含有来自未受刺激的小管的Cl-通道的由内而外的贴片和63%的来自毛喉素处理的CTAL小管的贴片的标准化电流。不可水解的ATP类似物腺苷5 '-腺苷酰亚胺二磷酸（AMP-PNP）不增加通道活性。在有ATP存在的浴中加入蛋白激酶A的催化亚基，增加了58%来自未受刺激的小管的由内而外的小通道的活性，但对45 pS通道没有影响。氯离子通道阻断剂5-硝基-2-（3-苯基丙胺）-苯甲酸（NPPB）、4，4 '-二异硫氰酸基芪-2，2'-二磺酸（DIDS）或格列本脲（浓度均为0.1 mmol l（-1））和二苯胺-2-羧酸（DPC）（浓度为1 mmol l（-1））可抑制由内向外贴片中小通道活性的80-100%。这些结果表明，两个Cl-通道具有对比的性能介导的基底外侧步骤的氯化钠吸收在厚的上升肢体的亨利环。
1. Chloride channels were identified in the basolateral membrane of isolated cortical thick ascending limbs (CTALs) of the mouse nephron by the patch-clamp technique. A channel with a conductance of 45 pS, previously shown to be Cl- selective, was detected in 21% of cell-attached patches when CTAL fragments were pre-incubated with 10 mu mol l(-1) forskolin for at least 15 min. The same channel was found in only 8.5% of cell-attached patches formed on unstimulated tubules.2. Another channel with a smaller conductance (7-9 pS) was found in 42.8% of cell-attached patches and 57% of inside-out patches in unstimulated CTAL tubules, but in 82-87% of patches from forskolin-treated tubules.3. The small channel was Cl- selective (Cl--to-Na+ permeability ratio, P-Cl/P-Na = 9.8) with the permeability sequence: NO3- > Br- > Cl- > F- > gluconate. Channel activity decreased (Br-) or disappeared (NO3-) at negative voltages. At 140 mmol l(-1), I- completely inhibited channel activity at all voltages, but a P-I/P-Cl ratio of 1.6 was estimated using a low concentration (10 mmol l(-1)).4. Internal adenosine triphosphate (ATP) increased normalized current (nP(o)) in 48% of inside-out patches containing Cl- channel from unstimulated tubules and in 63% of patches from forskolin-treated CTAL tubules. The non-hydrolysable ATP analogue, adenosine 5'-adenylyl imidodiphosphate (AMP-PNP) did not increase channel activity.5. Adding the catalytic subunit of protein kinase A to the bath in the presence of ATP increased the activity of the small channel in 58% of inside-out patches from unstimulated tubules, but it had no effect on the 45 pS channel.6. The Cl- channel blockers 5-nitro-2-(3-phenylpropylamine)-benzoic acid (NPPB), 4,4'-diisothiocyanatostilbene-2,2'- disulphonic acid (DIDS) or glibenclamide, all at 0.1 mmol l(-1) and diphenylamine-2-carboxylic acid (DPC), at 1 mmol l(-1), inhibited the small channel activity by 80-100% in inside-out patches.7. These results indicate that two Cl- channels with contrasting properties mediate the basolateral step of NaCl absorption in the thick ascending limb of the loop of Henle.