Time course of mechanical efficiency during afterloaded contractions in isolated cardiac muscle.
The time course of mechanical efficiency during working contractions in rabbit papillary muscle is presented. Efficiency is found to remain relatively constant during the working portion of the twitch, when the muscle is contracting against a constant load. As afterload was decreased, efficiency increased to 65 +/- 11% (mean +/- SE, n = 3) at 10% developed force at maximum length. This is in contrast to muscle work, which reached a peak of 3.0 +/- 0.3 (n = 6) mJ/g at 50% developed force at maximum length.
Department of Physiology and Biophysics, University of Vermont, College of Medicine, Burlington 05405.
J N
JN
Peterson
N R
NR
Alpert
D000818:Animals; D001831:Body Temperature; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction; D010210:Papillary Muscles / Q000502:physiology*; D011817:Rabbits; D013997:Time Factors