title: T-tubule remodelling and ryanodine receptor organization modulate sodium-calcium exchange.
abstract: The Na(+)/Ca(2+) exchanger (NCX) is a key regulator of intracellular Ca(2+) in cardiac myocytes, predominantly contributing to Ca(2+) removal during the diastolic relaxation process but also modulating excitation-contraction coupling. NCX is preferentially located in the T-tubules and can be close to or within the dyad, where L-type Ca(2+) channels face ryanodine receptors (RyRs), the Ca(2+) release channels of the sarcoplasmic reticulum. However, especially in larger animals, not all RyRs are in dyads or adjacent to T-tubules, and a substantial fraction of Ca(2+) release from the sarcoplasmic reticulum thus occurs at distance from NCX. This chapter deals with the functional consequences of NCX location and how NCX can modulate diastolic and systolic Ca(2+) events. The loss of T-tubules and the effects on RyR function and NCX modulation are explored, as well as quantitative measurement of local Ca(2+) gradients at the level of the dyadic space.
authors.affiliation: Department of Cardiovascular Diseases, University of Leuven, Leuven, Belgium. Karin.Sipido@med.kuleuven.be
authors.forename: Karin R
authors.initials: KR
authors.lastname: Sipido
authors.forename: Károly
authors.initials: K
authors.lastname: Acsai
authors.forename: Gudrun
authors.initials: G
authors.lastname: Antoons
authors.forename: Virginie
authors.initials: V
authors.lastname: Bito
authors.forename: Niall
authors.initials: N
authors.lastname: Macquaide
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020746:Calcium Channels, L-Type / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000378:metabolism*; D019837:Ryanodine Receptor Calcium Release Channel / Q000235:genetics / Q000378:metabolism*; D012519:Sarcoplasmic Reticulum / Q000235:genetics / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*; D019831:Sodium-Calcium Exchanger / Q000235:genetics / Q000378:metabolism*
chemical_list: D020746:Calcium Channels, L-Type; D009124:Muscle Proteins; D019837:Ryanodine Receptor Calcium Release Channel; D019831:Sodium-Calcium Exchanger; D012964:Sodium; D002118:Calcium