AJP - Cell Physiology, Vol 233, Issue 1 1-C7, Copyright © 1977 by American Physiological Society
Rate of heat production related to degree of filament overlap in chick ALD muscle
Y. Matsumoto and A. M. McPhedran
The anterior latissimus dorsi (ALD) of chicks (2 wk old) was examined for
rate of heat liberation when the muscle was reversibly stretched from L0 to
about 1.6 L0. The "plateau" forces of isometric tetani were related to the
corresponding rates of heat liberation. Presumably, in this region of
length change the degree of overlap between the thick and thin filaments is
changing. If the amount of overlap is known, the number of heavy meromyosin
cross bridges in activity can be estimated. From this information, the
amount of liberated energy can be calculated for a single cross-bridge
cycling. In all of our measurements, there was heat production even at
muscle lengths so great that no filament overlap would have to be assumed.
This finding was incorported into the estimate for energy release per
cross-bridge cycling.
