Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.6.4.1 (myosin ATPase)
 1,140 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Alteration in the histochemical activity of myosin ATPase has been demonstrated in the soleus of adult rats after brief (A) and prolonged (B) intensive weight lifting exercises. The former represented 'high intensity-short duration' and the latter 'high intensity-prolonged duration' exercise. The data revealed a significant muscle hypertrophy (23-26%) in both the exercising groups. Whereas group A muscles showed a relative increase in the number of type II (FOG) fibres, accompanied by a hypertrophy of the type I or slow twitch-oxidative (SO) fibres, the soleus muscles in group B showed a significant decrease (P less than 0.01) in the number of type II (FOG) fibres, presumably owing to a conversion of type II (FOG) to type I (SO) fibres. It is hypothesized that strengthening exercise may enhance the activity of the 'fast type' of myosin ATPase in brief or static work, and the 'slow type' in prolonged or more dynamic high intensity work.
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PMID:Myosin ATPase activity after strengthening exercise. 14 22

Muscle performance and structure was studied in rat soleus muscle with limited blood supply in combination with chronic muscle stimulation. Blood supply to the lower leg was restricted by ligation of the common iliac artery, electrodes were implanted in the vicinity of the sciatic nerve and ankle flexors were denervated. Three days later, soleus and gastrocnemius muscles were stimulated at 4 Hz four times a day for a period of 20 min with 2 h intervals between stimulations; this procedure was continued for 4 days. Muscle performance, histochemistry and ultrastructure were studied on the eighth day after operation in these muscles and in ischaemic unstimulated muscles with denervated ankle flexors. Both were compared with control animals. Muscles with limited blood supply developed less isometric twitch tension than control muscles (peak twitch tension in ischaemic muscle was 60.3 +/- 4.8 g g-1 muscle, mean +/- S.E.M., compared to 79.7 +/- 6.9 g g-1 in control muscle; tensions after 5 min contraction were 54.5 +/- 5.5 g g-1 in ischaemic muscle compared to 70.6 +/- 6 g g-1 in controls). Stimulated muscles with limited blood supply had higher peak (85 +/- 16.6 g g-1) and final (87 +/- 12 g g-1) tensions, and also fatigued less than muscles with limited blood supply but no stimulation. Histochemical estimation of capillary density (by staining for alkaline phosphatase) and slow (SO) and fast (FOG) fibres (by myosin ATPase staining) revealed similar capillary to fibre ratios (2.5) and a similar proportion of FOG fibres (around 18%) in all muscles. The proportion of glycogen-depleted fibres (estimated from the periodic acid Schiff reaction, PAS) in muscles removed from animals 10 min after a 5 min period of isometric twitches was significantly lower in ischaemic muscles (45.1 +/- 1.9%) than in control (80.5 +/- 1.5%) or chronically stimulated ischaemic muscles (67.3 +/- 4.0%). Electron microscopy showed disorganised myofibrils with Z-line streaming in 7.48 +/- 3.04% of fibres in muscles with limited blood supply. Swollen and degenerated mitochondria, dilated sarcoplasmic reticulum and areas of disrupted sarcolemma were also observed. Stimulated ligated muscles showed a significantly lower proportion of fibres with disorganised filaments (0.65 +/- 0.32%) and other signs of damage were much less frequent. The reduced damage and improved performance of chronically stimulated slow muscle may be the result of improved microcirculation, preventing accumulation of lactate.
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PMID:Effect of activity on performance and morphology in ischaemic rat slow muscles. 223 Jun 37

As revealed by the NADH-diaphorase, SDH and myosin ATPase, the M. pectineus of the cat possesses at least 3 main kind of fibres, with different distribution on the superficial and deep portions of the muscle. The superficial portion revealed that 23.6% are FOG fibres: 17.8% are SO fibres and 58.6% are FG fibres. Already the deep portion revealed that 61.4% are FOG fibres: 14.5% are SO fibres and 24.1% are FG fibres. The myosin ATPase reaction was used to demonstrate contracting characteristics. These findings suggest that the movements of fast contraction of M. pectineus are predominant.
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PMID:Fibre types of M. pectineus of the cat (Felis domestica). 226 62

The effect of growth on the capillarity and fiber type composition of the diaphragm, soleus and extensor digitorum longus (EDL) muscles of rats weighing between 55 and 330 g have been studied. Muscle samples obtained from the anesthetized rat were rapidly frozen and sliced transversely in a cryostat. The sections were stained histochemically by the SDH method and the myosin ATPase method after preincubation at pH 4.3 to typify fibers (FG, FOG and SO fibers). To visualize capillaries, the myosin ATPase method after preincubation at pH 4.0 was used. The percentage of FOG fibers decreased in all muscles with growth. While the FG and SO fibers increased in the diaphragm, SO fibers increased in the soleus, and FG fibers increased in the EDL. The capillary density showed a hyperbolic decrease with growth in all muscles, while the number of capillaries around each fiber increased in all muscles with growth. It is concluded that growth causes the changing properties of the motoneurons and the new capillary formation in the diaphragm muscle, as well as the soleus and EDL muscles.
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PMID:Effect of growth on muscle capillarity and fiber type composition in rat diaphragm. 401 50

Muscle fibre type composition and distribution in the biceps brachii (long head) and triceps brachii (long head) of the rat and rabbit were investigated using the following histochemical techniques: myosin ATPase, with preincubation at pH 10.4 and 4.35; succinate dehydrogenase (SDH) and glycogen phosphorylase. The muscle fibres were classified into slow-twitch (SO), fast-twitch glycolytic (FG), fast-twitch oxidative glycolytic (FOG and FOg) and fast-twitch oxidative fibres (FO). Significant differences in the regional distribution of muscle fibre types have been observed between the rat and the rabbit. In the rat, SO fibres were restricted to the deep regions of both biceps and triceps brachii, whereas FG fibres were located in the intermediate and superficial regions (the superficial regions contained the highest percentages of FG fibres). In the rabbit, SO and FG fibres were spread over the entire muscle, although SO and FG fibres were most abundant in the deep and superficial regions respectively. These findings indicate that the biceps and triceps brachii are more regionalised in the rat than in the rabbit.
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PMID:Muscle fibre types and their distribution in the biceps and triceps brachii of the rat and rabbit. 964 21