Abstract
The hypothesis that calcium release from the sarcoplasmic reticulum
in cardiac muscle is induced by rises in free cytosolic calcium (Fabiato
1983, Am. J. Physiol 245) allows the possibility that the release
could be at least partly regenerative. There would then be a non-linear
relation between calcium current and calcium release. We have investigated
this possibility in a single-cell version of the rabbit-atrial model
developed by Hilgemann & Noble (1987, Proc. R. Soc. Lond. B 230).
The model predicts different voltage ranges of activation for calcium-dependent
processes (like the sodium-calcium exchange current, contraction
or Fura-2 signals) and the calcium current, in agreement with the
experimental results obtained by Earm et al. (1990, Proc. R. Soc.
Lond. B 240) on exchange current tails, Cannell et al. (1987, Science,
Wash. 238) by using Fura-2 signals, and Fedida et al. (1987, J. Physiol.,
Lond. 385) and Talo et al. (1988, Biology of isolated adult cardiac
myocytes) by using contraction. However, when the Fura-2 concentration
is sufficiently high (greater than 200 microM) the activation ranges
become very similar as the buffering properties of Fura-2 are sufficient
to remove the regenerative effect. It is therefore important to allow
for the buffering properties of calcium indicators when investigating
the correlation between calcium current and calcium release.
- 1972993
- action
- animals,
- atrial
- biological,
- calcium
- calcium,
- carrier
- channels,
- computer
- dose-response
- drug,
- exchanger,
- factors,
- function,
- gov't,
- heart
- heart,
- in
- kinetics,
- magnesium,
- mathematics,
- membrane
- models,
- node,
- non-u.s.
- patch-clamp
- potassium
- potentials,
- proteins,
- rabbits,
- relationship,
- research
- simulation,
- sinoatrial
- sodium,
- sodium-calcium
- software,
- support,
- techniques,
- time
- ventricles,
- vitro,
Users
Please
log in to take part in the discussion (add own reviews or comments).