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The effect of ADP on ATP-sensitive K+ channels in the insulin-secreting RINm5F cell line has been investigated with the help of single-channel current recording from saponin-permeabilized cells. ADP (100-500 microM) markedly activates K+ channels when added to the bath solution in contact with the membrane inside. ADP-beta-S cannot mimick this effect.(More)
K+ channels that can be inhibited by intracellular ATP have been found in many different cell types. In the insulin-secreting pancreatic islet cells these channels are of crucial importance for stimulus-secretion coupling as glucose stimulation closes the ATP-sensitive channels which leads to depolarization and firing of Ca2+ action potentials. We now(More)
pharmacological agents that are able to influence the pancreatic B-cell? Work in our laboratory has been generously funded by project/equipment grants to M. In trod uction In a number of cells, including the pancreatic B-cell, cytoplasmic free Ca2+ ([Ca2+Ii) has a fundamental role in signal transduction. Over the years we have +-induced CaZ + release. 'To(More)
The single-channel current recording technique has been used to study the effects of diazoxide, tolbutamide and ATP, separately and combined, on the gating of nucleotide-regulated K+ channels in the insulin-secreting cell line RINm5F. The effects of diazoxide, tolbutamide and ATP4- were studied at the intracellular membrane surface, using the open-cell(More)
In patch-clamp records of K+ ATP channels in an insulin-secreting cell line (RINm5F) inhibition evoked by exposing the internal surface of the membrane to ATP is followed not just by the recovery of K+ ATP channel activity when the ATP is removed but by a marked activation of K+ ATP channels. This phenomenon is not a direct consequence of channel closure as(More)
The 31P-NMR technique has been used to assess the intracellular ratios and concentrations of mobile ATP and ADP and the intracellular pH in an insulin-secreting cell line, RINm5F. The single-channel current-recording technique has been used to investigate the effects of changes in the concentrations of ATP and ADP on the gating of nucleotide-dependent K+(More)
The Ca2+-activated K+ channel in rat pancreatic islet cells has been studied using patch-clamp single-channel current recording in excised inside-out and outside-out membrane patches. In membrane patches exposed to quasi-physiological cation gradients (Na+ outside, K+ inside) large outward current steps were observed when the membrane was depolarized. The(More)
K+ channels in cultured rat pancreatic islet cells have been studied using patch-clamp single-channel recording techniques in cell-attached and excised inside-out and outside-out membrane patches. Three different K+-selective channels have been found. Two inward rectifier K+ channels with slope conductances of about 4 and 17 pS recorded under(More)
OBJECTIVE Congenital hyperinsulinism in infancy (CHI) is characterized by unregulated insulin secretion from pancreatic β-cells; severe forms are associated with defects in ABCC8 and KCNJ11 genes encoding sulfonylurea receptor 1 (SUR1) and Kir6.2 subunits, which form ATP-sensitive K(+) (K(ATP)) channels in β-cells. Diazoxide therapy often fails in the(More)
The control of K+ channels in the insulin-secreting cell line RINm5F has been investigated by patch-clamp single-channel current recording experiments. The unitary current events recorded from cell-attached patches are due to large and small inwardly rectifying ATP-sensitive K+ channels with conductance properties similar to the two channels previously(More)