In this work we use a computer model of a ventricular
rabbit myocyte to study several factors that affect sarcoplasmic
reticulum (SR) calcium load, such as hypercalcemia,
SR calcium buffering, or ryanodine receptor (RyR2)
dynamics. General conditions for the appearance of calcium
spontaneous release in situations with calcium overload
are obtained. Furthermore, we study the appearance
of alternans under these conditions. The presence of calcium
alternans may be due to either a steep calcium load...
In this work we use a computer model of a ventricular
rabbit myocyte to study several factors that affect sarcoplasmic
reticulum (SR) calcium load, such as hypercalcemia,
SR calcium buffering, or ryanodine receptor (RyR2)
dynamics. General conditions for the appearance of calcium
spontaneous release in situations with calcium overload
are obtained. Furthermore, we study the appearance
of alternans under these conditions. The presence of calcium
alternans may be due to either a steep calcium load
release relation, resulting in oscillations in SR Ca content,
or to a slow recovery from refractoriness of the RyR2. We
find that a change in calsequestrin buffering dynamics or
extracellular calcium concentration greatly affects the appearance
of the former type of alternans, but not of the
latter.
Citation
Alvarez-Lacalle, E., Peñaranda, A., Rodriguez Cantalapiedra, I., Hove-Madsen, L., Echebarria, B. Effect of RyR2 refractoriness and hypercalcemia on calcium overload, spontaneous release, and calcium alternans. "Computing in Cardiology", 2013, vol. 40, p. 683-686.
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