Spark-to-wave transition: saltatory transmission of calcium waves
in cardiac myocytes.
Biophys. Chem., 72 (1-2):
87--100 (мая 1998)Аннотация
Using a modular approach, in which kinetic models of various mechanisms
of calcium handling in cells are fine-tuned to in vivo and in vitro
measurements before combining them into whole-cell models, three
distinct modes of transmission of calcium waves in mature and immature
frog eggs have been defined. Two modes of transmission are found
in immature eggs, where the inositol 1,4,5-trisphosphate receptor
(IP3R) controls release of calcium from the endoplasmic reticulum
(ER). The first mode corresponds to an excitable physiological state
of the cytoplasm and results in solitary waves that can appear as
circular or spiral waves in two dimensions with the wave speed proportional
to the square root of the diffusion constant of calcium. A second
mode occurs when the state of the cytoplasm is oscillatory and because
of the small size of the buffered diffusion constant for calcium,
the wave speed can appear to be weakly dependent on diffusion. In
the mature frog egg, where the sperm-induced Ca$^2+$ fertilization
wave is a propagating front, the cytoplasm appears to be bistable
and in this mode the wave speed is also proportional to the square
root of the diffusion constant. Here we investigate a fourth mode
of propagation for cardiac myocytes, in which calcium release from
the sarcoplasmic reticulum (SR) is dominated by clusters of ryanodine
receptors spaced at regular intervals. In myocytes a stochastically
excitable myoplasm leads to the spontaneous production of calcium
'sparks' that under certain conditions can merge into saltatory waves
with a speed proportional to the diffusion constant.
Описание
The whole bibliography file I use.