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Synchronization and propagation i n a ne twork o f electrically c oupled cells

Synchronization and propagation i n a ne twork o f electrically c oupled cells. =. =. =. =. =. QUIESCENT NRK CELLS. Cell dynamics of NRK cells. Cell dynamics of NRK cells. IP 3 receptor : Ca-induced Ca release Serca-pomp: CA terugpompen in ER PMCA-pomp: pompt Ca uit cytosol

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Synchronization and propagation i n a ne twork o f electrically c oupled cells

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  1. Synchronization and propagationin a network of electrically coupled cells = = = = =

  2. QUIESCENT NRK CELLS

  3. Cell dynamics of NRK cells

  4. Cell dynamics of NRK cells • IP3 receptor : Ca-induced Ca release • Serca-pomp: CA terugpompen in ER • PMCA-pomp: pompt Ca uit cytosol • Relevante ion-kanalen in celmembraan • ClCa : VCL = -20 mV • L-type Ca-kanaal : Vca = +55 mV • K-kanaal : VK = -75 mV • Ca-dependent Cl-channel (VCl = -20 mV)

  5. Cacyt/IP3 receptor model Calcium in cytosol increases, Calcium is the trigger

  6. Cacyt/IP3 receptor model Calcium and IP3 binding on the activating site of the VIP3 k1= 7 sec-1 m and w gates described as the Hodgkin-Huxley model

  7. Cacyt/IP3 receptor model For High levels of Calcium concentrations, the IP3 receptor is inhibited Mak et al. 1998

  8. Cacyt/IP3 receptor model Calcium concentration in the cytosol is recovered to its default value

  9. Cacyt/IP3 receptor model

  10. Intracellular Ca2+ and the action potential

  11. Frequency of Ca-oscillations as a function of IP3

  12. Ca-oscillation amplitude as a function of IP3 concentration

  13. Wat gebeurt er • Indien we 2 cellen hebben met elk een verschillende IP3 concentratie ? • Indien deze cellen elk een verschillende frequentie hebben voor de Ca-oscillaties • Indien de cellen electrisch gekoppeld zijn.

  14. Coupling between two cells Ca oscillaties Actie potentialen Geen electrische koppeling Zwakke electrische koppeling Sterke (normale) electrische koppeling

  15. Wat gebeurt er in een netwerk van cellen, waarbij sommige cellen wel/niet Ca oscillaties hebben ? • Een enkele cel is niet in staat in anderen cellen, die geen Ca-oscillaties hebben, AP’s te genereren: de stroom vloeit weg tgv hoge conductantie van gap-junctions • Indien er een groepje cellen is, dat tegelijk een AP genereert en dat voldoende cellen bevat, worden nabuurcellen tot vuren gebracht. • Cellen, die Ca-oscillaties vertonen bij verschillende frequenties, synchroniseren.

  16. Ca-oscillations and AP-firing in a network of coupled cells

  17. Ca-oscillations and AP-firing in a network of coupled cells

  18. Samenvatting • Cellen met intracellulaire Ca-oscillaties genereren actiepotentialen • Cellen met verschillende Ca-oscillatie frequenties kunnen synchroniseren • Indien voldoende cellen samen actief zijn, ontstaat propagatie van electrische activiteit in een netwerk. • Voorbeelden: darm, pancreas, NRK-cellen.

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