When [Na] was suddenly introduced to single muscle fibers (Xenopus or frog), which had been pretreated with Na-free solution (Tris-substituted), the time-course of twitch recovery was very variable, half-time ranging from less than 1 S to 5 S. The [Na] vs. twitch height relationship was also variable. In small Xenopus fibers, decreases of [Na] to 50% increased the twitch, while in large Xenopus...

The slow-twitch soleus muscle (SOL) exhibits decreased twitch tension (cold depression) in response to a decreased temperature, whereas the fast-twitch extensor digitorum longus (EDL) muscle shows enhanced twitch tension (cold potentiation). On the other hand, the slow-twitch SOL muscle is more sensitive to twitch potentiation and contractures evoked by caffeine than the fast-twitch EDL muscle....

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 snake transversus abdominis muscle is an extremely simple segmentally repeating muscle containing 80 to 100 muscle fibers in a single-fiber-thick sheet. This muscle exhibits a striking pattern of muscle fiber types: twitch fibers alternate with tonic fibers and, among the twitch fibers, slower and faster contracting subtypes also alternate. Thus, in many regions of the muscle the pattern of...

In small mammals, muscles with shorter twitch contraction times and a predominance of fast-twitch, type II fibers exhibit greater posttetanic twitch force potentiation than muscles with longer twitch contraction times and a predominance of slow-twitch, type I fibers. In humans, the correlation between potentiation and fiber-type distribution has not been found consistently. In the present study...

OBJECTIVES Previous studies showed that skeletal muscle microcirculation was reduced in chronic heart failure. The aim of this study was to investigate the effects of endurance training on capillary and arteriolar density of fast and slow twitch muscles in rats with chronic heart failure. MATERIALS AND METHODS Four weeks after surgeries (left anterior descending (LAD) artery occlusion), chron...

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...

Diaphragm strength can be assessed by measurement of transdiaphragmatic pressure (Pdi) in response to stimulation of the phrenic nerves. The length-tension relationship of the diaphragm can be studied by measuring twitch Pdi over the range of lung volume. Previous studies of the relationship between lung volume and diaphragm strength have used the technique of electrical stimulation of the phre...

Aerobic Power (VO2 max) and anaerobic power were estimated in medical students before and after six weeks of yogic training. A significant increase in aerobic power and a significant decrease in anaerobic power was observed. This may be due to conversion of some of the Fast Twitch (F.T.) muscle fibres into Slow Twitch fibres (S.T.) during yogic training.