Muscle Fiber Population and Biochemical Properties of Whole Body Muscles in Thoroughbred Horses
Article first published online: 2 SEP 2009
Copyright © 2009 Wiley-Liss, Inc.
The Anatomical Record
Volume 292, Issue 10, pages 1663–1669, October 2009
How to Cite
Kawai, M., Minami, Y., Sayama, Y., Kuwano, A., Hiraga, A. and Miyata, H. (2009), Muscle Fiber Population and Biochemical Properties of Whole Body Muscles in Thoroughbred Horses. Anat Rec, 292: 1663–1669. doi: 10.1002/ar.20961
- Issue published online: 18 SEP 2009
- Article first published online: 2 SEP 2009
- Manuscript Revised: 15 MAY 2009
- Manuscript Accepted: 15 MAY 2009
- Manuscript Received: 22 JAN 2009
- The Japanese Ministry of Education, Science and Culture. Grant Number: 21300251
- muscle fiber type;
- metabolic enzyme
We examine the muscle fiber population and metabolic properties of skeletal muscles from the whole body in Thoroughbred horses. Postmortem samples were taken from 46 sites in six Thoroughbred horses aged between 3 and 6 years. Fiber type population was determined on muscle fibers stained with monoclonal antibody to each myosin heavy chain isoform and metabolic enzyme activities were determined spectrophotometrically. Histochemical analysis demonstrated that most of the muscles had a high percentage of Type IIa fibers. In terms of the muscle characteristic in several parts of the horse body, the forelimb muscles had a higher percentage of Type IIa fiber and a significantly lower percentage of Type IIx fiber than the hindlimb muscles. The muscle fiber type populations in the thoracic and trunk portion were similar to those in the hindlimb portion. Biochemical analysis indicated high succinate dehydrogenase activity in respiratory-related muscle and high phosphofructokinase activity in hindlimbs. We suggested that the higher percentage of Type IIa fibers in Thoroughbred racehorses is attributed to training effects. To consider further the physiological significance of each part of the body, data for the recruitment pattern of each muscle fiber type during exercise are needed. The muscle fiber properties in this study combined with the recruitment data would provide fundamental information for physiological and pathological studies in Thoroughbred horses. Anat Rec, 2009. © 2009 Wiley-Liss, Inc.