Transverse stiffness of myofibrils of skeletal and cardiac muscles studied by atomic force microscopy.
The transverse stiffness of single myofibrils of skeletal and cardiac muscles was examined by atomic force microscopy. The microscopic images of both skeletal and cardiac myofibrils in a rigor state showed periodical striation patterns separated by Z-bands, which is characteristic of striated muscle fibers. However, sarcomere patterns were hardly distinguishable in the stiffness distributions of the relaxed myofibrils of skeletal and cardiac muscles. Myofibrils in a rigor state were significantly stiff compared with those in a relaxed state, and in each state, cardiac myofibrils were significantly stiffer compared with skeletal myofibrils. By proteolytic digestions of sarcomere components of myofibrils, it was suggested that cardiac myofibrils are laterally stiffer than skeletal myofibrils because Z-bands, connectin (titin) filament networks, and other components of sarcomere structures for the former myofibrils are stronger than those for the latter.
Akiyama
Nao
N
Department of Physics (Biophysics Section), Faculty of Science, Tokyo University of Science, Tokyo, Japan.
Ohnuki
Yoshiki
Y
Kunioka
Yuki
Y
Saeki
Yasutake
Y
Yamada
Takenori
T
D000818:Animals; D002154:Calpain / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D018625:Microscopy, Atomic Force; D009119:Muscle Contraction; D018485:Muscle Fibers, Skeletal / Q000502:physiology* / Q000648:ultrastructure; D009124:Muscle Proteins / Q000378:metabolism; D009200:Myocardial Contraction; D032383:Myocytes, Cardiac / Q000502:physiology* / Q000648:ultrastructure; D009210:Myofibrils / Q000000981:diagnostic imaging* / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D012518:Sarcomeres / Q000502:physiology / Q000648:ultrastructure; D014357:Trypsin / Q000494:pharmacology; D014463:Ultrasonography
D009124:Muscle Proteins; D014357:Trypsin; D002154:Calpain