Minimal Model for Intracellular Calcium Oscillations and Electrical Bursting in Melanotrope Cells of Xenopus Laevis

  • Authors:

  • L. Niels Cornelisse;Wim J. J. M. Scheenen;Werner J. H. Koopman;Eric W. Roubos;Stan C. A. M. Gielen

  • Affiliations:

  • Department of Cellular Animal Physiology and Department of Biophysics, Nijmegen Institute for Neurosciences, University of Nijmegen, 6525 ED Nijmegen, The Netherlands;Department of Cellular Animal Physiology, Nijmegen Institute for Neurosciences, University of Nijmegen, 6525 E Nijmegen, The Netherlands;Department of Cellular Animal Physiology, Nijmegen Institute for Neurosciences, University of Nijmegen, 6525 E Nijmegen, The Netherlands;Department of Cellular Animal Physiology, Nijmegen Institute for Neurosciences, University of Nijmegen, 6525 E Nijmegen, The Netherlands;Department of Biophysics, Nijmegen Institute for Neurosciences, University of Nijmegen, 6525 EZ Nijmegen, The Netherlands

  • Venue:
  • Neural Computation
  • Year:
  • 2001

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Abstract

A minimal model is presented to explain changes in frequency, shape, and amplitude of Ca2+ oscillations in the neuroendocrine melanotrope cell of Xenopus Laevis. It describes the cell as a plasma membrane oscillator with influx of extracellular Ca2+ via voltage-gated Ca2+ channels in the plasma membrane. The Ca2+ oscillations in the Xenopus melanotrope show specific features that cannot be explained by previous models for electrically bursting cells using one set of parameters. The model assumes a KCa-channel with slow Ca2+-dependent gating kinetics that initiates and terminates the bursts. The slow kinetics of this channel cause an activation of the KCa-channel with a phase shift relative to the intracellular Ca2+ concentration. The phase shift, together with the presence of a Na+ channel that has a lower threshold than the Ca2+ channel, generate the characteristic features of the Ca2+ oscillations in the Xenopus melanotrope cell.