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Changes in cytoplasmic ATP concentration parallels changes in ATP‐regulated K + ‐channel activity in insulin‐secreting cells
Author(s) -
Köhler Martin,
Norgren Svante,
Berggren Per-Olof,
Fredholm Bertil B,
Larsson Olof,
Rhodes Christopher J,
Herbert Terence P,
Luthman Holger
Publication year - 1998
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)01539-7
Subject(s) - luciferase , transfection , extracellular , cytoplasm , luciferin , adenosine triphosphate , chemistry , biophysics , biochemistry , biology , microbiology and biotechnology , gene
Changes in cytoplasmic ATP concentration were monitored in intact insulin‐producing cells and correlated to changes in the activity of ATP‐sensitive K + ‐channels (K ATP channels). Luciferase was introduced into HIT M2.2 cells and whole pancreatic islets by transient expression of firefly ( Photinus pyralis ) luciferase cDNA. In transfected cells, extracellular addition of luciferin increased the luminescence signal to a maximum within 50–120 s. Addition of 1 μM of the mitochondrial uncoupler FCCP decreased the luminescence, an effect partly reversed upon withdrawal of the compound. High concentrations of glucose increased cytoplasmic free ATP concentration. Changes in the luminescence signal were accompanied by changes in activity of the ATP‐sensitive K + ‐channel. Transfection per se did not deteroriate cell function, as verified by experiments showing similar changes in cytoplasmic free Ca 2+ ‐concentration, [Ca 2+ ] i , in both transfected and non‐transfected cells. By measuring the cytoplasmic ATP concentration and K ATP channel activity under similar experimental conditions, it was possible to establish, for the first time, a direct relationship between these two parameters. This indeed suggests that the cytoplasmic ATP concentration has a crucial role in the regulation of K ATP channel activity under physiological conditions.