title: Progressive disorganization of the excitation-contraction coupling apparatus in aging human skeletal muscle as revealed by electron microscopy: a possible role in the decline of muscle performance.
abstract: An impairment of the mechanisms controlling the release of calcium from internal stores (excitation-contraction [EC] coupling) has been proposed to contribute to the age-related decline of muscle performance that accompanies aging (EC uncoupling theory). EC coupling in muscle fibers occurs at the junctions between sarcoplasmic reticulum and transverse tubules, in structures called calcium release units (CRUs). We studied the frequency, cellular localization, and ultrastructure of CRUs in human muscle biopsies from male and female participants with ages ranging from 28 to 83 years. Our results show significant alterations in the CRUs' morphology and cellular disposition, and a significant decrease in their frequency between control and aged samples: 24.4/100 microm(2) (n = 2) versus 11.6/100 microm(2) (n = 7). These data indicate that in aging humans the EC coupling apparatus undergoes a partial disarrangement and a spatial reorganization that could interfere with an efficient delivery of Ca(2+) ions to the contractile proteins.
authors.affiliation: CeSI, Centro Scienze dell'Invecchiamento, Università degli Studi G. d'Annunzio, Chieti, CH I-66013, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Boncompagni
authors.forename: Luigi
authors.initials: L
authors.lastname: d'Amelio
authors.forename: Stefania
authors.initials: S
authors.lastname: Fulle
authors.forename: Giorgio
authors.initials: G
authors.lastname: Fanò
authors.forename: Feliciano
authors.initials: F
authors.lastname: Protasi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000473:pathology* / Q000502:physiology; D002118:Calcium / Q000378:metabolism; D020746:Calcium Channels, L-Type / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D046529:Microscopy, Electron, Transmission; D008875:Middle Aged; D009119:Muscle Contraction; D018485:Muscle Fibers, Skeletal / Q000648:ultrastructure; D018482:Muscle, Skeletal / Q000502:physiology* / Q000648:ultrastructure*; D019837:Ryanodine Receptor Calcium Release Channel / Q000502:physiology
chemical_list: D020746:Calcium Channels, L-Type; D019837:Ryanodine Receptor Calcium Release Channel; D002118:Calcium