The Journal of Membrane Biology ( IF 2.3 ) Pub Date : 2021-07-27 , DOI: 10.1007/s00232-021-00193-y Kate A Bowley 1 , Geoffrey I Sandle 1
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Intermediate conductance potassium (IKCa) channels are exquisitively Ca2+ sensitive, intracellular Ca2+ regulating channel activity by complexing with calmodulin (CaM), which is bound to the cytosolic carboxyl tail. Although CaM antagonists might be expected to decrease IKCa channel activity, the effect of W-7 in human T lymphocytes are conflicting. We therefore evaluated the effect of W-7 on basolateral IKCa channels in human colonic crypt cells. Intact crypts obtained from normal human colonic biopsies by Ca2+ chelation were used for patch clamp studies of basolateral IKCa channels in the cell-attached configuration. IKCa channel activity was studied when the bath Ca2+ concentration was changed from 1.2 mmol/L to 100 μmol/L and back to 1.2 mmol/L, as well as from 100 μmol/L to 1.2 mmol/L and back to 100 μmol/L, both in the absence and presence of 25 μmol/L W-7. Decreasing bath Ca2+ from 1.2 mmol/L to 100 μmol/L decreased IKCa channel activity reversibly in the absence of W-7, whereas there was a uniformly high level of channel activity at both bath Ca2+ concentrations in the presence of W-7. In separate experiments, increasing bath Ca2+ from 100 μmol/L to 1.2 mmol/L increased IKCa channel activity reversibly in the absence of W-7, whereas there was again a uniformly high level of channel activity at both bath Ca2+ concentrations in the presence of W-7. We, therefore, propose that W-7 has a specific stimulatory effect on basolateral IKCa channel activity, despite its ability to inhibit Ca2+/CaM-mediated, IKCa channel-dependent Cl− secretion in human colonic epithelial cells.
Graphic Abstract
中文翻译：
钙调素拮抗剂 W-7 增强人结肠隐窝中的中间电导 Ca2+- 敏感基底外侧钾通道 (IKCa) 活性
中间电导钾 (IK Ca ) 通道对 Ca 2+非常敏感，细胞内 Ca 2+通过与与胞质羧基尾部结合的钙调蛋白 (CaM) 复合来调节通道活性。尽管预计 CaM 拮抗剂会降低 IK Ca通道活性，但 W-7 在人 T 淋巴细胞中的作用是相互矛盾的。因此，我们评估了 W-7 对人结肠隐窝细胞基底外侧 IK Ca通道的影响。通过Ca 2+螯合从正常人结肠活检获得的完整隐窝用于细胞附着构型中基底外侧IK Ca通道的膜片钳研究。钾钙研究了镀液 Ca 2+浓度从 1.2 mmol/L 到 100 μmol/L 再回到 1.2 mmol/L，以及从 100 μmol/L 到 1.2 mmol/L 再回到 100 μmol/时的通道活性。 L，在不存在和存在 25 μmol/L W-7 的情况下。在没有 W-7 的情况下，将浴 Ca 2+从 1.2 mmol/L 降低到 100 μmol/L 会可逆地降低 IK Ca通道活性，而在存在 W-7 的情况下，两种浴 Ca 2+浓度下的通道活性水平都一致。 W-7。在单独的实验中，将浴 Ca 2+从 100 μmol/L 增加到 1.2 mmol/L 会增加 IK Ca在没有 W-7 的情况下，通道活性是可逆的，而在 W-7 存在的情况下，在两种浴 Ca 2+浓度下，通道活性再次保持一致的高水平。因此，我们提出 W-7 对基底外侧 IK Ca通道活性具有特异性刺激作用，尽管它能够抑制人结肠上皮细胞中 Ca 2+ /CaM 介导的 IK Ca通道依赖性 Cl -分泌。
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