Zünkler B J, Lins S, Ohno-Shosaku T, Trube G, Panten U
Institut für Pharmakologie und Toxikologie, Universität Göttingen, FRG.
FEBS Lett. 1988 Nov 7;239(2):241-4. doi: 10.1016/0014-5793(88)80925-6.
The effects of intracellular purine nucleotides on tolbutamide-induced block of ATP-dependent K+ channels from mouse pancreatic B-cells were studied using the patch-clamp technique. When applied to the inside of excised patches, tolbutamide alone blocked channel activity half-maximally at 55 microM and the concentration-response curve for the inhibition of K+ channels by tolbutamide was flat. ADP (1 mM), but not other nucleotides (AMP, GTP or GDP) increased the steepness of the concentration-response curve and decreased the half-maximally effective tolbutamide concentration to 4.2 microM. It is suggested that the ATP-dependent K+ channel or a closely related structure contains a receptor which is accessible for cytosolic ADP and controls the sensitivity to tolbutamide.
利用膜片钳技术研究了细胞内嘌呤核苷酸对甲苯磺丁脲诱导的小鼠胰腺β细胞ATP依赖性钾通道阻断作用的影响。当将甲苯磺丁脲应用于切除膜片的内侧时，单独使用甲苯磺丁脲在55μM时可使通道活性半数最大阻断，且甲苯磺丁脲抑制钾通道的浓度-反应曲线是平坦的。ADP（1 mM）可增加浓度-反应曲线的斜率，并将甲苯磺丁脲的半数最大有效浓度降低至4.2μM，而其他核苷酸（AMP、GTP或GDP）则无此作用。提示ATP依赖性钾通道或与之密切相关的结构含有一个可被胞质ADP作用的受体，并控制对甲苯磺丁脲的敏感性。
