Mechanical and Histochemical Characterization of Skeletal Muscles from Senescent Rats

Document Type




Format of Original

10 p.

Publication Date



American Physiological Society

Source Publication

American Journal of Physiology - Cell Physiology

Source ISSN


Original Item ID

DOI: 10.1152/ajpcell.1986.251.3.C421


Maximal shortening velocity (Vmax) and isometric tension (Po) were measured in living fiber bundles and skinned fibers from extensor digitorum longus (EDL) and soleus (SOL) muscles of young adult (9 mo) and senescent (30 mo) Fisher 344 rats. The fiber type composition of each muscle preparation was determined using myosin (M)-ATPase histochemistry. Vmax, determined by the slack test method, was unchanged in the EDL but was increased in the SOL muscles of young adult vs. senescent rats. Velocities determined at intermediate loads using the load-stepping technique were slower for EDL bundles but were nearly identical for SOL bundles from senescent vs. young adult rats. Po was greater in SOL and was unchanged in EDL bundles and skinned fibers from senescent vs. young adult rats. M-ATPase histochemistry and Vmax were in agreement for fast and slow muscle bundles and fibers. The relationship between tension and pCa (i.e.,--log[Ca2+]) in skinned fibers from each muscle was similar in both age groups. Sodium dodecyl sulfate-polyacrylamide gels of the skinned fibers consistently showed fast light chains (LCs) in the EDL fibers and slow LCs in the SOL fibers, with no apparent age-related differences.


American Journal of Physiology - Cell Physiology, Vol. 251, No. 3 (September 1, 1986): C421-C430. DOI.

Thomas Eddinger was affiliated with the University of Wisconsin - Madison at the time of publication.