Pflügers Archiv

, 452:222

Scaling of skeletal muscle shortening velocity in mammals representing a 100,000-fold difference in body size

  • James O. Marx
  • M. Charlotte Olsson
  • Lars Larsson
Skeletal Muscle

DOI: 10.1007/s00424-005-0017-6

Cite this article as:
Marx, J.O., Olsson, M.C. & Larsson, L. Pflugers Arch - Eur J Physiol (2006) 452: 222. doi:10.1007/s00424-005-0017-6

Abstract

To fully understand the effect of scaling on skeletal muscle shortening velocity (V0), it is important to know which phenotypic characteristics drive the changes between species. The purpose of the current investigation was to compare the effects of body mass and femur length, as an estimate of total limb length, on V0 in species that cover a 100,000-fold range of body masses. Using the slack test procedure, V0 was determined for fibers expressing types I and IIa myosin heavy chain (MyHC) isoforms in the mouse, rat, dog, human, horse, and rhinoceros under identical experimental conditions. A significant scaling effect on V0 was detected when compared to body mass (type I fibers, r=0.95, p<0.01; type IIa fibers, r=0.83, p<0.05). However, the horse’s V0 for both fiber types was faster than the human’s, despite having a 5-fold greater body mass than the human. When V0 was scaled vs limb length, the strength of the relationships improved in fibers expressing both types I and IIa MyHC (r=0.98, p<0.001, and r=0.89, p<0.05, respectively) and scaled with the expected relationship, with the species with the shorter femur, the horse, having the faster V0. A similar effect can be seen with stride frequency scaling more closely with limb length than body mass. These results suggest that limb length, not body mass, is a more relevant factor driving the scaling effect on skeletal muscle shortening velocity.

Keywords

ScalingMyosin heavy chainShortening velocityFast- and slow-twitch muscle

Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • James O. Marx
    • 1
  • M. Charlotte Olsson
    • 2
  • Lars Larsson
    • 2
    • 3
  1. 1.Department of BiologyThe University of PennsylvaniaPhiladelphiaUSA
  2. 2.Department of Clinical NeurophysiologyUppsala University HospitalUppsalaSweden
  3. 3.Center for Developmental and Health GeneticsThe Pennsylvania State UniversityUniversity ParkUSA