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The cell-attached configuration of the patch clamp technique was used for studying slow variations in the activity of the ATP-sensitive K+ channels in pancreatic beta-cells isolated from mouse and man. In 0 or 3 mM glucose, the fraction of time the channels were open exhibited oscillations with frequencies in the 0.25-0.40/min range. This phenomenon is a(More)
The role of voltage-dependent Ca2+ entry for glucose generation of slow oscillations of the cytoplasmic Ca2+ concentration ([Ca2+]i) was evaluated in individual mouse pancreatic beta-cells. Like depolarization with K+, a rise of the glucose concentration resulted in an enhanced influx of Mn2+, which was inhibited by nifedipine. This antagonist of L-type(More)
The role of Ca2+ in initiating exocytosis of granule-bound secretory products was evaluated with respect to pancreatic islet hormones. Apart from stimulating the transfer of the granules to the plasma membrane and their subsequent extrusion, a rise of the cytoplasmic Ca2+ concentration ([Ca2+]i) may under certain conditions also have depressive effects on(More)
The effects of the nonmetabolizable amino acid alpha-aminoisobutyric acid (AIB) on insulin release were evaluated using beta cell-rich pancreatic islets from ob/ob mice. Both AIB and L-alanine promptly induced transient insulin release during column perifusion of islet cells. The secretory response was dependent on an elevated level of glucose and(More)
Individual pancreatic beta cells respond to glucose stimulation with large amplitude (300-500 nM) oscillations in the cytoplasmic Ca2+ concentration ([Ca2+]i). These oscillations (frequency 0.05-0.5/min) depend on rhythmical depolarization of the plasma membrane, with influx of Ca2+ through voltage-operated channels, but do not require intracellular(More)
The glucose effect on insulin release in a Ca(2+)-deficient medium was analyzed in perifusion experiments with aggregates of cells prepared by dispersal of the beta-cell-rich pancreatic islets of ob/ob-mice. Hyperosmolar additions of 20 mM D-glucose or its poorly metabolized transport analogue 3-0-methyl-D-glucose resulted in 50% suppression of the(More)
A procedure is described for changing the medium surrounding individual cells attached to the bottom of a cell chamber. A small hole at the "apex" of a plastic U-tube allowed application and withdrawal of medium. The medium to be applied was perfused through the U-tube by pressure at one end and suction at the other. To prevent premature delivery of new(More)
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