Impact of mitochondrial Ca2+ cycling on pattern formation and stability.
Energization of mitochondria significantly alters the pattern of Ca2+ wave activity mediated by activation of the inositol (1,4,5) trisphosphate (IP3) receptor (IP3R) in Xenopus oocytes. The number of pulsatile foci is reduced and spiral Ca2+ waves are no longer observed. Rather, target patterns of Ca2+ release predominate, and when fragmented, fail to form spirals. Ca2+ wave velocity, amplitude, decay time, and periodicity are also increased. We have simulated these experimental findings by supplementing an existing mathematical model with a differential equation for mitochondrial Ca2+ uptake and release. Our calculations show that mitochondrial Ca2+ efflux plays a critical role in pattern formation by prolonging the recovery time of IP3Rs from a refractory state. We also show that under conditions of high energization of mitochondria, the Ca2+ dynamics can become bistable with a second stable stationary state of high resting Ca2+ concentration.
Falcke
M
M
Max Planck Institute for Physics of Complex Systems, 01187 Dresden, Germany.
Hudson
J L
JL
Camacho
P
P
Lechleiter
J D
JD
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D003600:Cytosol / Q000378:metabolism; D015544:Inositol 1,4,5-Trisphosphate / Q000494:pharmacology; D007700:Kinetics; D008293:Malates / Q000494:pharmacology; D018613:Microscopy, Confocal; D008928:Mitochondria / Q000378:metabolism*; D008962:Models, Theoretical; D009865:Oocytes / Q000378:metabolism; D019289:Pyruvic Acid / Q000494:pharmacology; D014981:Xenopus
D008293:Malates; C030298:malic acid; D015544:Inositol 1,4,5-Trisphosphate; D019289:Pyruvic Acid; D002118:Calcium