Shape, Size, and Distribution of Ca2+ Release Units and Couplons in Skeletal and Cardiac Muscles

摘要: Excitation contraction (e-c) coupling in skeletal and cardiac muscles involves an interaction between specialized junctional domains of the sarcoplasmic reticulum (SR) exterior membranes (either surface membrane or transverse (T) tubules). This 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 membranes; ryanodine (RyRs), SR. Special muscle are constituted by SR bearing RyRs that not associated with (the corbular extended EjSR). Functional groupings DHPRs within have been couplons, term is also loosely applied EjSR muscle. Knowledge structure, geometry, disposition couplons understand mechanism during activation. paper presents a compilation quantitative data on variety muscles, which useful modeling events, both macroscopic microscopic ("sparks").