CHANGES OF MEMBRANE CURRENTS IN CARDIAC-CELLS INDUCED BY LONG WHOLE-CELL RECORDINGS AND TOLBUTAMIDE
CHANGES OF MEMBRANE CURRENTS IN CARDIAC-CELLS INDUCED BY LONG WHOLE-CELL RECORDINGS AND TOLBUTAMIDE
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DOI：
10.1007/bf00584657
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发表时间：
1987-08-01
影响因子：
4.5
通讯作者：
TRUBE, G
中科院分区：
文献类型：
--
作者：
BELLES, B;HESCHELER, J;TRUBE, G
分离的单个心肌细胞取自成年豚鼠的心脏。膜片钳技术的全细胞记录结构用于膜电流的测量。在长时间(1-3h)的记录过程中，观察到钙离子内向电流的减少(减慢)和非时间依赖性的K+外向电流的增加。外向电流产生的时间依赖于移液管内的ATP浓度，这表明该电流与Noma和Shibaski(1985)所描述的依赖于ATP的K+电流是相同的。然而，在实验中达到的最大外向电流与ATP浓度无关，这表明ATP在细胞内部的扩散是有限的。在分离的细胞膜上的单通道实验和全细胞记录中，降血糖的磺脲甲苯丁胺可阻断ATP依赖的K+电流。0.38 mM的IC50大约是报道的胰腺β细胞的50倍(Trube等人。1986)。甲苯磺丁胺(3 MM)对钙内向电流和内向整流钾电流无影响。
Single isolated myocytes were obtained from the ventricles of adult guinea pig hearts. The whole-cell recording configuration of the patch-clamp technique was used to measure membrane currents. A decrease (run-down) of the Ca2+ inward current and increase of a time-independent K+ outward current were observed during long lasting (1-3 h) recordings. The time at which the outward current developed depended on the intracellular ATP concentration in the pipette, suggesting that this current is identical to the ATP-dependent K+ current described by Noma and Shibaski (1985). However, the maximum outward current reached in the experiments was independent of the ATP concentration indicating a limited diffusion of ATP in the cell interior. In single-channel experiments on isolated patches of cell membrane and in whole-cell recordings the ATP-dependent K+ current could be blocked by the hypoglycaemic sulphonylurea tolbutamide. The IC50 of 0.38 mM was about 50 times higher than that reported for pancreatic .beta.-cells (Trube et al. 1986). The Ca2+ inward current and the inwardly rectifying K+ current were not affected by tolbutamide (3 mM).