Increased tetanic force and reduced myoplasmic [pi] following a
brief series of tetani in mouse soleus muscle.
Bruton, Joseph D., Charlott Wretman, Abram Katz, and H[angstrom]akan
Westerblad.
Department of Physiology and Pharmacology and Department of
Clinical Physiology, Karolinska Institute, S-171 77 Stockholm,
Sweden
APStracts 3:0383C, 1996.
Muscle performance is improved after a brief period of exercise (warm
-up). One factor which is known to strongly affect force production is
the myoplasmic concentration of inorganic phosphate ([Pi]). Improved
performance following warm-up may therefore be due to a reduction of
[Pi]. Herein we show that following a warm-up protocol (15 tetani at
2 s intervals), tetanic force is increased by about 6% (p < 0.05)
and [Pi] is almost halved (p < 0.05) in isolated mouse soleus
muscle. A warm-up protocol with longer intervals (15 tetani at 5 s
intervals) reduced tetanic force and did not alter [Pi]. We conclude
that a reduction of [Pi ] contributes to the force-potentiating
effect of warm-up.
Received 30 April 1996; accepted in final form 21 October 1996.
APS Manuscript Number C230-6.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 31 December 1996