Rotation of actin monomers during isometric contraction of skeletal muscle.
J Biomed Opt
; 12(1): 014013, 2007.
Article
em En
| MEDLINE
| ID: mdl-17343488
ABSTRACT
Cyclic interactions of myosin and actin are responsible for contraction of muscle. It is not self-evident, however, that the mechanical cycle occurs during steady-state isometric contraction where no work is produced. Studying cross-bridge dynamics during isometric steady-state contraction requires an equilibrium time-resolved method (not involving application of a transient). This work introduces such a method, which analyzes fluctuations of anisotropy of a few actin molecules in muscle. Fluorescence anisotropy, indicating orientation of an actin protomer, is collected from a volume of a few attoliters (10(-18) L) by confocal total internal reflection (CTIR) microscopy. In this method, the detection volume is made shallow by TIR illumination, and narrow by confocal aperture inserted in the conjugate image plane. The signal is contributed by approximately 12 labeled actin molecules. Shortening of a myofibril during contraction is prevented by light cross-linking with 1-ethyl-3-[3-dimethylamino)-propyl]-carbodiimide. The root mean-squared anisotropy fluctuations are greater in isometrically contracting than in rigor myofibrils. The results support the view that during isometric contraction, cross-bridges undergo a mechanical cycle.
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Base de dados:
MEDLINE
Assunto principal:
Actinas
/
Músculo Esquelético
/
Contração Isométrica
/
Miofibrilas
Idioma:
En
Revista:
J Biomed Opt
Assunto da revista:
ENGENHARIA BIOMEDICA
/
OFTALMOLOGIA
Ano de publicação:
2007
Tipo de documento:
Article
País de afiliação:
Estados Unidos