Abstract
Computer-assisted modeling of calcium influx through voltage-activated
membrane channels predicted that buffer-limited elevation of cytoplasmic
free calcium ion concentration occurs within microscopic hemispherical
"domains" centered upon the active Ca channels. With increasing depolarization,
the number of activated channels, and hence the number of Ca domains,
should increase; the single-channel current should, however, decrease,
thereby decreasing Ca$^2+$ accumulation in each domain relative
to the macroscopic current. Such voltage dependence of the microscopic
distribution of Ca$^2+$ may influence relations between total
Ca$^2+$ entry and Ca-dependent processes. Ca-mediated inactivation
of Ca channels in Aplysia neurons exhibits behavior consistent with
the calcium domain hypothesis.
- 6329349
- animals,
- aplysia,
- biological,
- calcium,
- channels,
- comparative
- computers,
- electrochemistry,
- gov't,
- ion
- kinetics,
- membrane
- models,
- neurons,
- non-p.h.s.,
- p.h.s.,
- potentials,
- research
- study,
- support,
- u.s.
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