Scattered light intensity fluctuations (SLIF) (which monitor spontaneous Ca2+ release from the sarcoplasmic reticulum [SR]) and resting and twitch tension were measured during intervals after stimulation in rat and rabbit papillary muscles. For 1 to 5 seconds after stimulation of rat muscle bathed in 1.5 mM [Ca2+] (Cao), twitch and resting tension are depressed and SLIF are transiently abolishe...

We have cloned a group of cDNAs that encodes the skeletal ryanodine receptor isoform (RyR1) of fish from a blue marlin extraocular muscle library. The cDNAs encode a protein of 5,081 amino acids with a calculated molecular mass of 576,302 Da. The deduced amino acid sequence shows strong sequence identity to previously characterized RyR1 isoforms. An RNA probe derived from a clone of the full-le...

Skeletal muscle is composed of diverse fiber types, yet the underlying molecular mechanisms responsible for this diversification remain unclear. Herein, we report that the extracellular signal-regulated kinase (ERK) 1/2 pathway, but not p38 or c-Jun NH(2)-terminal kinase (JNK), is preferentially activated in fast-twitch muscles. Pharmacological blocking of ERK1/2 pathway increased slow-twitch f...

Twitch and tonic muscle fibers of snake skeletal muscle differ in their synpatic as well as mechanical properties. These experiments were aimed at detemining the basis of the difference in vesicular release properties of nerve terminals at twitch and tonic endplates. Miniature endplate currents (MEPCs) were recorded from voltage-clamped garter snake muscle fibers depolarized by high K+ in eithe...

The effect of Odonthobuthos doriae (O.d) scorpion venom at 0/3, 1 and 3, 10 µg/ml concentrations were investigated on nerve-muscle transmission, using the Twitch tension technique. A concentration of 0.3 µg/ml caused a small change in the twitch height in response to indirect muscle stimulation, but higher concentrations (1, 3, 10 µg/ml) caused a transient augmentation in twitch response follow...

The effect of Odonthobuthos doriae (O.d) scorpion venom at 0/3, 1 and 3, 10 µg/ml concentrations were investigated on nerve-muscle transmission, using the Twitch tension technique. A concentration of 0.3 µg/ml caused a small change in the twitch height in response to indirect muscle stimulation, but higher concentrations (1, 3, 10 µg/ml) caused a transient augmentation in twitch response follow...

Background. SIRT3 is one of the members of the Sirtuin deacetylase protein family which is linked to the longevity of human being and is used as an important therapeutic and diagnostic marker in illness and aging. Objectives. The aim of this study was studying the effect of continuous swimming training on some biomarkers of longevity in slowtwitch (SOL) and fast-twitch (EDL) muscles of adult m...

Smooth muscle expresses in its endoplasmic reticulum an isoform of the Ca2+-transport ATPase that is very similar to or identical with that of the cardiac-muscle/slow-twitch skeletal-muscle form. However, this enzyme differs from that found in fast-twitch skeletal muscle. This conclusion is based on two independent sets of observations, namely immunological observations and phosphorylation expe...

Introduction: Ethanol is a suitable solvent for many in vivo and ex studies. However, it can interfere with normal muscle contraction make variations the results. Contrary to present study, previous investigations revealed suppressant effect of ethanol on contraction. Methods: This study was based an isolated chick biventer cervicis nerve-muscle using twitch tension recording technique. Nerve c...

Unfused tetanic contractions evoked by trains of stimuli at variable interpulse intervals (IPIs) were recorded for 10 fast fatigable (FF), 10 fast resistant (FR), and 10 slow (S) motor units (MUs) and subsequently decomposed with a mathematical algorithm into trains of twitch-shape responses to successive stimuli. The mean stimulation frequencies were matched for each MU to evoke tetani of simi...