This review compiles quantitative data on the structure, geometry, and disposition of couplons in skeletal and cardiac muscles to aid in modeling macroscopic and microscopic calcium release events.
Provides a compilation of quantitative structural data on calcium release units and couplons in muscle cells to aid in modeling calcium release events.
Excitation contraction (e-c) coupling in skeletal and cardiac muscles involves an interaction between specialized junctional domains of the sarcoplasmic reticulum (SR) and of exterior membranes (either surface membrane or transverse (T) tubules). This interaction occurs at special structures named calcium release units (CRUs). CRUs contain two proteins essential to e-c coupling: dihydropyridine receptors (DHPRs), L-type Ca(2+) channels of exterior membranes; and ryanodine receptors (RyRs), the Ca(2+) release channels of the SR. Special CRUs in cardiac muscle are constituted by SR domains bearing RyRs that are not associated with exterior membranes (the corbular and extended junctional SR or EjSR). Functional groupings of RyRs and DHPRs within calcium release units have been named couplons, and the term is also loosely applied to the EjSR of cardiac muscle. Knowledge of the structure, geometry, and disposition of couplons is essential to understand the mechanism of Ca(2+) release during muscle activation. This paper presents a compilation of quantitative data on couplons in a variety of skeletal and cardiac muscles, which is useful in modeling calcium release events, both macroscopic and microscopic ("sparks").
Franzini‐Armstrong et al. (1999) conducted a review in Skeletal and cardiac muscle physiology. This review compiles quantitative data on the structure, geometry, and disposition of couplons in skeletal and cardiac muscles to aid in modeling macroscopic and microscopic calcium release events.