Synchronization and propagation i n a ne twork o f electrically c oupled cells
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Transcript of Synchronization and propagation i n a ne twork o f electrically c oupled cells
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Synchronization and propagation in a network of electrically coupled cells
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QUIESCENT NRK CELLS
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Cell dynamics of NRK cells
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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)
Cell dynamics of NRK cells
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Cacyt/IP3 receptor model
Calcium in cytosol increases, Calcium is the trigger
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Cacyt/IP3 receptor model
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k1= 7 sec-1
Calcium and IP3 binding on the activating site of the VIP3
m and w gates described as the Hodgkin-Huxley model
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Cacyt/IP3 receptor model
Mak et al. 1998
For High levels of Calcium concentrations, the IP3 receptor is inhibited
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Cacyt/IP3 receptor model
Calcium concentration in the cytosol is recovered to its default value
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Cacyt/IP3 receptor model
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Intracellular Ca2+ and the action potential
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Frequency of Ca-oscillations as a function of IP3
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Ca-oscillation amplitude as a function of IP3 concentration
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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.
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Coupling between two cells
Geen electrische
koppeling
Zwakke electrische
koppeling
Sterke (normale)
electrische
koppeling
Ca oscillaties Actie potentialen
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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.
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Ca-oscillations and AP-firing in a network of coupled cells
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Ca-oscillations and AP-firing in a network of coupled cells
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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.