Stress-dependent and -independent expression of the myogenic regulatory factors and the MARP genes after eccentric contractions in rats

• The relationship between muscle mechanical conditions and gene expression was investigated by varying both stress and contraction mode imposed upon rat dorsiflexors (n= 25), activating them at high or low frequencies (150 Hz or 40 Hz) either eccentrically or isometrically. Muscle physiological, immunohistochemical and gene expression changes were then measured 24 h after the exercise bout. Peak stress was the best predictor of muscle injury, independent of contraction mode (i.e. eccentric or isometric). When peak stresses were matched, no physiological or immunohistochemical differences were detected between isometric and eccentric contractions. The expression of certain myogenic regulatory and muscle ankyrin repeat protein (MARP) genes (myoD, myogenin, MLP and CARP) depended both on peak muscle stress achieved during contraction and contraction mode. In contrast, Arpp/Ankrd2 was dramatically upregulated only by eccentric contractions, but not by isometric contractions, even though the stress level of the eccentric contractions varied over a three-fold range and overlapped with that of the isometric group. The role that Arpp/Ankrd2 upregulation plays in the biological response to eccentric contraction remains to be determined, as does the control mechanism whereby the expression of certain genes (such as myoD, myogenin, MLP and CARP) is sensitive to muscle stress while another (Arpp/Ankrd2) is sensitive only to contraction mode.

Subject headings

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Kirurgi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Surgery (hsv//eng)

Keyword

Animals

Desmin/metabolism

Fibronectins

Gene Expression Regulation

Immunohistochemistry

Isometric Contraction

Male

Models

Animal

Multivariate Analysis

Muscle Proteins/*genetics/metabolism

Muscle

Skeletal/injuries/metabolism

MyoD Protein/genetics/metabolism

Myogenin/genetics/metabolism

RNA

Messenger/metabolism

Rats

Rats

Sprague-Dawley

Regression Analysis

Repressor Proteins/*genetics/metabolism

Stress

Mechanical

Time Factors

Vimentin/metabolism

Publication and Content Type

ref (subject category)

art (subject category)