title: Increased tetanic force and reduced myoplasmic [P(i)] following a brief series of tetani in mouse soleus muscle.
abstract: Muscle performance is improved after a brief period of exercise (warm-up). One factor that is known to strongly affect force production is the myoplasmic concentration of inorganic phosphate ([P(i)]). Improved performance after warm-up may therefore be due to a reduction of [P(i)]. Herein, we show that after a warm-up protocol (15 tetani at 2-s intervals), tetanic force is increased by approximately 6% (P < 0.05) and [P(i)] 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 [P(i)]. We conclude that a reduction of [P(i)] contributes to the force-potentiating effect of warm-up.
authors.affiliation: Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden.
authors.forename: J D
authors.initials: JD
authors.lastname: Bruton
authors.forename: C
authors.initials: C
authors.lastname: Wretman
authors.forename: A
authors.initials: A
authors.lastname: Katz
authors.forename: H
authors.initials: H
authors.lastname: Westerblad
mesh_terms: D000818:Animals; D003593:Cytoplasm / Q000378:metabolism; D004734:Energy Metabolism; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D018482:Muscle, Skeletal / Q000378:metabolism*; D009200:Myocardial Contraction; D010710:Phosphates / Q000378:metabolism*; D013746:Tetany; D013997:Time Factors
chemical_list: D010710:Phosphates