Vladimir Matchkov

Activation of a cGMP-sensitive calcium-dependent chloride channel may cause transition from calcium waves to whole-cell oscillations in smooth muscle cells.

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  • Jens Christian Jacobsen, University of Copenhagen, Denmark
  • Christian Aalkjær
  • Holger Nilsson, Denmark
  • Vladimir Matchkov
  • Jacob Freiberg, University of Copenhagen, Denmark
  • Niels-Henrik Holstein-Rathlou, University of Copenhagen, Denmark
  • Danish Biomembrane Research Centre
In vitro, alpha-adreno receptor stimulation of rat mesenteric small arteries often leads to a rhythmic change in wall tension, vasomotion. Within the individual smooth muscle cells of the vascular wall, vasomotion is often preceded by a period of asynchronous calcium waves. Abruptly, these low-frequency waves may transform into high-frequency whole-cell calcium oscillations. Simultaneously, multiple cells synchronize leading to rhythmic generation of tension. We present a mathematical model of vascular smooth muscle cells that aims at characterizing this sudden transition. Simulations show calcium waves sweeping through the cytoplasm when the SR is stimulated to release calcium. A rise in cyclic guanosine monophosphate (cGMP) leads to the experimentally observed transition from waves to whole-cell calcium oscillations. At the same time membrane potential starts to oscillate and the frequency approximately doubles. In this transition, the simulated results point to a key role for a recently discovered cGMP-sensitive calcium-dependent chloride channel. This channel depolarizes the membrane in response to calcium released from the SR. In turn, depolarization causes uniform opening of L-type calcium channels on the cell surface stimulating synchronized release of SR-calcium and inducing the shift from waves to whole-cell oscillations. The effect of the channel is therefore to couple the processes of the SR with those of the membrane. We hypothesize that the shift in oscillatory mode and the associated onset of oscillations in membrane potential within the individual cell may underlie sudden intercellular synchronization and the appearance of vasomotion. Key words: Vasomotion, Chloride channel, cGMP, Mathematical model, Calcium waves.
Original languageEnglish
JournalAmerican Journal of Physiology
Volume293
Issue1
Pages (from-to)H215-H228
Number of pages14
Publication statusPublished - 2007

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