Computational model of excitable cell indicates ATP free energy dynamics in response to calcium oscillations are undampened by cytosolic ATP buffers.
Syst Biol (Stevenage)
; 153(5): 405-8, 2006 Sep.
Article
en En
| MEDLINE
| ID: mdl-16986328
Mitochondria in excitable cells are recurrently exposed to pulsatile calcium gradients that activate cell function. Rapid calcium uptake by the mitochondria has previously been shown to cause uncoupling of oxidative phosphorylation. To test (i) if periodic nerve firing may cause oscillation of the cytosolic thermodynamic potential of ATP hydrolysis and (ii) if cytosolic adenylate (AK) and creatine kinase (CK) ATP buffering reactions dampen such oscillations, a lumped kinetic model of an excitable cell capturing major aspects of the physiology has been developed. Activation of ATP metabolism by low-frequency calcium pulses caused large oscillation of the cytosolic, but not mitochondrial ATP/ADP, ratio. This outcome was independent of net ATP synthesis or hydrolysis during mitochondrial calcium uptake. The AK/CK ATP buffering reactions dampened the amplitude and rate of cytosolic ATP/ADP changes on a timescale of seconds, but not milliseconds. These model predictions suggest that alternative sources of capacitance in neurons and striated muscles should be considered to protect ATP-free energy-driven cell functions.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Adenosina Trifosfato
/
Calcio
/
Señalización del Calcio
/
Mitocondrias
/
Modelos Neurológicos
/
Neuronas
Tipo de estudio:
Prognostic_studies
Límite:
Animals
/
Humans
Idioma:
En
Revista:
Syst Biol (Stevenage)
Asunto de la revista:
BIOLOGIA
Año:
2006
Tipo del documento:
Article
País de afiliación:
Países Bajos
Pais de publicación:
Reino Unido