Аннотация
Based on realistic mechanisms of Ca$^2+$ buffering that include
both stationary and mobile buffers, we derive and investigate models
of Ca$^2+$ diffusion in the presence of rapid buffers. We obtain
a single transport equation for Ca$^2+$ that contains the effects
caused by both stationary and mobile buffers. For stationary buffers
alone, we obtain an expression for the effective diffusion constant
of Ca$^2+$ that depends on local Ca$^2+$ concentrations.
Mobile buffers, such as fura-2, BAPTA, or small endogenous proteins,
give rise to a transport equation that is no longer strictly diffusive.
Calculations are presented to show that these effects can modify
greatly the manner and rate at which Ca$^2+$ diffuses in cells,
and we compare these results with recent measurements by Allbritton
et al. (1992). As a prelude to work on Ca$^2+$ waves, we use
a simplified version of our model of the activation and inhibition
of the IP3 receptor Ca$^2+$ channel in the ER membrane to illustrate
the way in which Ca$^2+$ buffering can affect both the amplitude
and existence of Ca$^2+$ oscillations.
- 7919012
- acid,
- animals,
- biological,
- buffers,
- calcium,
- cations,
- divalent,
- dyes,
- egtazic
- factors,
- fluorescent
- fura-2,
- gov't,
- kinetics,
- mathematics,
- models,
- non-p.h.s.,
- non-u.s.
- oscillometry,
- research
- support,
- time
- u.s.
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