Abstract
The control of calcium release from intracellular stores (the sarcoplasmic
reticulum) in cardiac muscle was examined with the use of a confocal
microscope and voltage clamp techniques. Depolarization evoked graded
calcium release by altering the extent of spatial and temporal summation
of elementary calcium release events called "calcium sparks." These
evoked sparks were triggered by local L-type calcium channel currents
in a stochastic manner, were similar at different potentials, and
resembled spontaneous calcium sparks. Once triggered, the calcium
release from the sarcoplasmic reticulum during a calcium spark was
independent of the duration of the triggering calcium influx. These
results were used to develop a unifying model for cardiac excitation-contraction
coupling that explains the large (but paradoxically stable) amplification
of the trigger calcium influx by a combination of digital and analog
behavior.
- 7754384
- animals,
- calcium
- calcium,
- channel
- channel,
- channels,
- confocal,
- ga,
- gov't,
- in
- ion
- membrane
- microscopy,
- muscle
- myocardium,
- non-u.s.
- p.h.s.,
- patch-clamp
- potentials,
- probability,
- proteins,
- rats,
- receptor
- release
- research
- reticulum,
- ryanodine
- sarcoplasmic
- support,
- techniques,
- ting,
- u.s.
- vitro,
Users
Please
log in to take part in the discussion (add own reviews or comments).