Minimal model for intracellular calcium oscillations and electrical bursting in melanotrope cells of Xenopus laevis.
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.
Cornelisse
L N
LN
Department of Cellular Animal Physiology, Nijmegen Institute for Neurosciences, University of Nijmegen, The Netherlands.
Scheenen
W J
WJ
Koopman
W J
WJ
Roubos
E W
EW
Gielen
S C
SC
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D004594:Electrophysiology; D007425:Intracellular Membranes / Q000378:metabolism*; D009074:Melanocyte-Stimulating Hormones / Q000378:metabolism*; D008564:Membrane Potentials / Q000502:physiology; D008959:Models, Neurological; D009991:Oscillometry; D009994:Osmolar Concentration; D010902:Pituitary Gland / Q000166:cytology / Q000502:physiology*; D015222:Sodium Channels / Q000502:physiology; D014982:Xenopus laevis / Q000502:physiology*
D015222:Sodium Channels; D009074:Melanocyte-Stimulating Hormones; D002118:Calcium