Abstract
Two types of K channel regulated by ATP were observed in pancreatic β cells from a type-2 diabetic man. One type had a conductance of 67 pS at-70 mV in symmetrical 140 mM KCl and was inhibited by intracellular ATP with a half-maximal concentration of 40 μM. ATP inhibition was antagonised by ADP. Tolbutamide inhibited the whole-cell K currents half-maximally at 25 μM. This channel has properties similar to those found for the ATP-sensitive K channel in rodent and normal human β cells. The second channel type observed was an ATP-activated K channel. It had a conductance of 37 pS at -70 mV in symmetrical 140 mM KCl and was activated half-maximally by 9 μM intracellular ATP. This channel was unaffected by 1 mM tolbutamide. In cell-attached patches, one β cell out of four tested responded to 20 mM glucose with depolarization. The role of the ATP-activated K channel with respect to the (patho)physiology of the β cell is uncertain.
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Williams, B.A., Smith, P.A., Leow, K. et al. Two types of potassium channel regulated by ATP in pancreatic B cells isolated from a type-2 diabetic human. Pflugers Arch. 423, 265–273 (1993). https://doi.org/10.1007/BF00374405
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DOI: https://doi.org/10.1007/BF00374405