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  • Insulin Secretion  (1)
  • Oscillations  (1)
  • Pancreatic B-cells  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Significance of ionic fluxes and changes in membrane potential for stimulus-secretion coupling in pancreatic B-cells (1984)
    Springer
    Cellular and molecular life sciences 40 (1984), S. 1043-1052 
    Details
    ISSN: 1420-9071
    Keywords: Pancreatic B-cells ; ions ; insulin release ; membrane potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Conclusions This brief review has tried to shed some light on the mechanisms and significance of the changes in membrane potential and in ionic fluxes occurring in B-cells upon glucose stimulation. There is now strong evidence that, under physiological conditions at least, these electrical events-and the underlying modifications of ionic permeabilities and fluxes — play a causal role in the stimulation of insulin release. It also seems clear that certain accompanying ionic fluxes have no direct stimulatory role, but may be important in maintaining cellular homeostasis. Recent experimental evidence has also shown that the electrical activity in B-cells is not an all-or-none stereotypic response. Not only can its intensity be adjusted to the magnitude of the stimulus, but its characteristics can also be modulated by potentiators Our knowledge of the stimulus-secretion coupling has markedly progressed over the past few years, but elucidation of several important steps remains a challenging goal. There is no doubt that parallel measurements of insulin release, of ionic fluxes and of membrane potential in B-cells will still contribute to that understanding.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01971450
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Cyclic variations of glucose-induced electrical activity in pancreatic B cells (1982)
    Springer
    Pflügers Archiv 393 (1982), S. 322-327 
    Details
    ISSN: 1432-2013
    Keywords: Pancreatic B cell ; Membrane potential ; Electrical activity ; Oscillations ; Glucose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Microelectrodes were used to record the effects of glucose on the membrane potential of single mouse B cells. In most cells, the slow waves of depolarization and the intervals of repolarization produced by a constant concentration of glucose displayed a great regularity. However, cyclic variations in the duration of these slow waves and/or intervals were observed in a certain number of B cells. These oscillations were more clearly visible and more frequent (47%) in the presence of 15 mM glucose, than in the presence of 10 mM glucose (19%). They sometimes disappeared with time, but sometimes persisted for over 90 min and were not affected by atropine, propanolol and phentolamine. Their mean period was 203 s at 10 mM glucose and 235 s at 15 mM glucose. The membrane potential and the degree of electrical activity were not different in B cells exhibiting these cyclic variations or not. These oscillations in the duration of slow waves and intervals induced by glucose could be due to fluctuations in metabolic events and in cytoplasmic K+ activity in B cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00581418
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Membrane potential of beta-cells in pancreatic islets (1974)
    Springer
    Pflügers Archiv 351 (1974), S. 195-206 
    Details
    ISSN: 1432-2013
    Keywords: Pancreatic Islets ; β-cells ; Electrical Activity ; Insulin Secretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Intracellular microelectrode techniques have been used to investigate the membrane potential and electrical activity of β-cells of Langerhans islets of mice. In Krebs-Henseleit solution containing substimulatory glucose concentrations, i.e. concentrations which do not produce an insulin release, β-cells showed no electrical activity. In this concentration range an increase of glucose concentration depolarized the membrane without inducing spike activity. The β-cells became electrically active in glucose concentrations known to produce insulin secretion. The type of electrical activity depended on glucose concentration. Between 5.5 and 16.6 mM glucose it generally occured in bursts. Each was initiated by a depolarization of about 10 mV to a plateau level from which irregular spikes with frequencies up to 12/sec arose. The burst ended with a repolarization phase to the original potential level. With increasing glucose concentration the duration of the bursts increased and the intervals between the bursts shortened. Above 16.6 mM glucose the burst activity usually changed into continuous activity. If the relative duration of burst activity is plotted against glucose concentration there is a sigmoid relationship similar to that known to exist between insulin release and glucose concentration. TTX had no effect on burst activity. Removal of [Ca]o inhibited burst activity. Occasionally at zero [Ca]o action potential-like spikes were observed. Re-introduction of [Ca]o initially increased the frequency of these action potential-like spikes and then led to the usual glucose induced burst activity. The significance of the results is discussed in relation to the mechanism of insulin release.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00586918
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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