Skeletal muscle of guinea pigs is composed of at least three types of fibers which are distinguishable by their kinetic and histochemical properties. Fast twitch muscles may be histochemically red or white; fragmented sarcoplasmic reticulum (FSR) prepared from both types of fast twitch muscles has identical calcium-accumulating capacity (maximal calcium uptake) and calcium-concentrating ability...

Isometric single-twitch force and intracellular Ca2+ transients were recorded simultaneously, using fura-2, from slow- and fast-twitch muscle fibres of the rat, mouse and Etruscan shrew Suncus etruscus. In the slow-twitch rat soleus, force half-relaxation time was three times longer than the 50% decay time of the fura-2 signal. In contrast, in the fast-twitch extensor digitorum longus muscles o...

Parvalbumin (PV), a small cytosolic protein belonging to the family of EF-hand calcium-binding proteins, is highly expressed in mammalian fast-twitch muscle fibers. By acting as a 'slow-onset' Ca2+ buffer, PV does not affect the rapid contraction phase, but significantly contributes to increase the rate of relaxation, as demonstrated in PV-/- mice. Unexpectedly, PV-/- fast-twitch muscles were c...

Functional properties of in situ mitochondria and of mitochondrial creatine kinase were studied in saponin-skinned fibers taken from normal and M-creatine kinase-deficient mice. In control animals, apparent Km values of mitochondrial respiration for ADP in cardiac (ventricular) and slow-twitch (soleus) muscles (137 +/- 16 microM and 209 +/- 10 microM, respectively) were manyfold higher than tha...

abstractbackground and objective: satellite cells are muscle stem cells that enter cycle cells due to myotrauma. among activation and proliferation indices of these cells is increase of myod gene expression. but these are contradiction in response of this gene to resistance exercise in fast and slow fibers. thus, the aim of this study was to evaluate the effect of a single bout of resistance ex...