A minimal gating model for the cardiac calcium release channel.
AUTOR(ES)
Zahradníková, A
RESUMO
A Markovian model of the cardiac Ca release channel, based on experimental single-channel gating data, was constructed to understand the transient nature of Ca release. The rate constants for a minimal gating scheme with one Ca-free resting state, and with two open and three closed states with one bound Ca2+, were optimized to simulate the following experimental findings. In steady state the channel displays three modes of activity: inactivated 1 mode without openings, low-activity L mode with single openings, and high-activity H mode with bursts of openings. At the onset of a Ca2+ step, the channel first activates in H mode and then slowly relaxes to a mixture of all three modes, the distribution of which depends on the new Ca2+. The corresponding ensemble current shows rapid activation, which is followed by a slow partial inactivation. The transient reactivation of the channel (increment detection) in response to successive additions of Ca2+ is then explained by the model as a gradual recruitment of channels from the extant pool of channels in the resting state. For channels in a living cell, the model predicts a high level of peak activation, a high extent of inactivation, and rapid deactivation, which could underlie the observed characteristics of the elementary release events (calcium sparks).
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1233789Documentos Relacionados
- Single-channel events and gating behavior of the cardiac gap junction channel.
- Electrophysiological effects of ryanodine derivatives on the sheep cardiac sarcoplasmic reticulum calcium-release channel.
- Description of modal gating of the cardiac calcium release channel in planar lipid membranes.
- Charged local anesthetics block ionic conduction in the sheep cardiac sarcoplasmic reticulum calcium release channel.
- Phosphorylation targets the functional gating of a glutamate channel.