Journal of Applied Physiology, Vol 60, Issue 4 1393-1400, Copyright © 1986 by American Physiological Society
Correlation between histochemistry and muscle activity of jaw muscles in cats
G. C. Gorniak
Studies on limb muscles of mammals indicate that the pattern of
electromyographic (EMG) activity reflects the histochemical profile of the
muscle. This relationship suggests that EMG activity may permit a
prediction of certain morphological characteristics of the muscle being
studied. In this study numerical descriptors of EMG activity of the
masticatory muscles of cats are correlated with the distribution of fiber
types, as well as with fiber and fascicle areas, to test the extent to
which EMG can be used to predict regional morphology. The results show that
the level of EMG activity and its duration have a significant positive
correlation with the percentage of slow- and fast-twitch fatigue-resistant
fibers and a significant negative correlation with the percentage of
fast-twitch fatigable fibers and the ratio of fast-twitch fatigable to
fast-twitch fatigue-resistant, plus slow fibers. No correlation was found
between activity and fiber cross-sectional area; the descriptors showing
significant correlation vary with the hardness of the food. Thus the level
of EMG activity and its duration seemingly do provide an indicator of the
relative difference in fiber distribution among muscles in a species.
