In situ rat fast skeletal muscle is more efficient at submaximal than at maximal activation levels.

Content Provider	Semantic Scholar
Author	Abbate, Fabio Ruiter, Cornelis J. De Offringa, C. Sargeant, Anthony Haan, Arnold De
Copyright Year	2002
Abstract	The influence of stimulation frequency on efficiency (= total work output/high-energy phosphate consumption) was studied using in situ medial gastrocnemius muscle tendon complexes of the rat. The muscles performed 20 repeated concentric contractions (2/s) at 34 degrees C. During these repeated contractions, the muscle was stimulated via the severed sciatic nerve with either 60, 90, or 150 Hz. The muscle was freeze-clamped immediately after these contractions, and high-energy phosphate consumption was determined by measuring intramuscular chemical change relative to control muscles. The average values (+/-SD) of efficiency calculated for 60, 90, and 150 Hz were 18.5 +/- 1.5 (n = 7), 18.6 +/- 1.5 (n = 9), and 14.7 +/- 1.3 mJ/micromol phosphate (n = 9). The results indicate that the efficiency of the muscles that were submaximally activated (60 or 90 Hz) was higher (+26%, P < 0.05) than that of those maximally activated (150 Hz). Additional experiments showed that the low efficiency at maximal activation levels is unlikely to be the result of a higher energy turnover by the Ca2+ -ATPase relative to the total energy turnover. Therefore, alternative explanations are discussed.
Starting Page	495
Ending Page	508
Page Count	14
File Format	PDF HTM / HTML
Alternate Webpage(s)	http://jap.physiology.org/content/jap/92/5/2089.full.pdf
PubMed reference number	11960961v1
Volume Number	92
Issue Number	5
Journal	Journal of applied physiology
Language	English
Access Restriction	Open
Subject Keyword	Carbamoyl-Phosphate Synthase I Deficiency Disease Gastrocnemius muscle structure Hertz (Hz) Micromole Skeletal muscle structure Structure of sciatic nerve Tendon structure explanation inorganic phosphate
Content Type	Text
Resource Type	Article