Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.6.4.1 (myosin ATPase)
1,140 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Quadriceps strength, relaxation rate, fibre-type composition and energy-turnover rate during a submaximal contraction have been measured in hypo- and hyper-thyroid patients and compared with findings in normal subjects. 2. Six out of eight hypothyroid patients had normal strength whereas four out of five hyperthyroid patients were weak. 3. Relaxation rate was decreased in all the hypothyroid patients but increased in only three out of five hyperthyroid patients. 4. In hypothyroidism there was a marked reduction in the percentage contributed by type II fibres to muscle cross-section, partly due to type II atrophy but also due to a decrease in the relative frequency of type II fibres. In hyperthyroidism both fibre types tended to atrophy. 5. The rate of ATP turnover during submaximal contraction held to fatigue was reduced in hypothyroidism. This was probably due to decreased ATP utilization rather than an impaired supply of energy-supplying substrates. In hyperthyroidism the rate of ATP turnover was increased. 6. Altered relaxation rate and ATP-turnover rate may be explained on the basis of changes in myosin ATPase activity with thyroid status. Changes in muscle-fibre-type composition, as determined histochemically, could not per se account for the functional abnormalities.
...
PMID:Muscle relaxation rate, fibre-type composition and energy turnover in hyper- and hypo-thyroid patients. 50 76

The intrinsic laryngeal muscles of the horse, donkey, sheep, ox, pig, dog and cat were examined for myosin ATPase, following acid and alkali pre-incubation, SDH and M-alphaGPDH activities. In all laryngeal muscles two fibre types, betaR and alphaR, belonging to slow and fast-contracting, fatigue-resistant motor units (types S and FR) were present in different proportions. The alphaW fibre type, belonging to fast-contracting and fatigue-resistant motor units was absent (type FF). The alphaR fibres of the dog and the cat were subdivided into groups by the various degrees of acid stable myosin ATPase, oxidative and glycolytic activities. In the ox and pig laryngeal muscles, the same fibres showed an atypical myosin ATPase activity, as high as the fast-contracting fibres but acid-resistant like the slow-twitch fibres. The most uniform muscle was the CAD, which was formed of a higher percentage of slow-twitch fibres than the other laryngeal muscles of the same species. Also the VE muscle was very uniform in the dog, horse and donkey but the fast-twitch fibres were by far the most numerous, the highest in fact among all the laryngeal muscles. In the TA muscle of the cat, sheep and ox, the percentage of fast-twitch fibres was very high in the rostral portion decreasing gradually towards the caudal portion. Thus it was possible to separate histochemically the TA muscle in the rostral (pars ventricularis) and caudal (pars vocalis) portions which are related to the VE and the VO muscles of the dog, horse and donkey. In the VO muscle the slow-twitch fibres are more numerous than in the VE. The two portions of the TA were not detected by histochemical methods in the pig. However, this muscle has the highest percentage of fast-twitch fibres. The qualitative and quantitative data presented in this paper together with the data reported in the literature, enable us to correlate morphological and functional aspects of fibre composition among the species.
...
PMID:A comparative histochemical study of intrinsic laryngeal muscles of ungulates and carnivores. 53 8

The aim of the present study was to further subdivide the type II fibers of the human thyroarytenoid and posterior cricoarytenoid muscles by means of a modified myosin ATPase reaction. In order to understand the functioning of these highly strained muscles better, it is important to know the respective percentage of fatigue-resistant type IIA fibers and fatigable type IIB fibers. The material comprised the larynges of seven laryngectomized males aged between 45 and 70 years and four laryngectomized females aged between 39 and 72 years. After having been frozen in nitrogen, 10-microns-thick sections were cut from the laryngeal muscles in a cryostat. The pH-lability of the enzyme that can be utilized in a classical myosin ATPase reaction permits a differentiation between fiber types I, IIA and IIB. Evidently, this is not possible with every human muscle. The fiber types IIA and IIB of the thyroarytenoid and the posterior cricoarytenoid muscles could be clearly distinguished by means of the inhibition reactivation myofibrillar ATPase technique. Using this method, the myosin ATPase enzyme was initially inhibited by hydroxymercuribenzoate and subsequently reactivated by cysteine. Regarding the incidence of type I and IIA fibers, there was a statistically significant difference between the thyroarytenoid and the posterior cricoarytenoid muscles. The type IIA fiber content was statistically significantly higher in the arytenoid muscle than in the posterior cricoarytenoid muscle. The percentage of type IIB fibers was low, not only in the thyroarytenoid muscle and the posterior cricoarytenoid muscle but also in the other laryngeal muscles.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Fiber differentiation of the human laryngeal muscles using the inhibition reactivation myofibrillar ATPase technique. 141 83

We studied the fiber types and contractile properties of the extensor digitorum longus (EDL) and soleus (SOL) muscles from young adult mice, rats and guinea pigs, and the correlation between these two parameters. Individual fibers in both muscles were classified as fast-twitch glycolytic (FG), fast-twitch oxidative glycolytic (FOG) or slow-twitch oxidative (SO) fibers according to Peter et al., and type II B, II A, or I fibers according to Brooke & Kaiser. Contractile properties were measured in situ at 37 degrees C. The isometric twitch contraction time (CT) and one-half relaxation time (1/2 RT) tended to be shortened in proportion to the area occupied by type II fibers, and type II B fibers. However, the differences between CT and fiber types were not always uniform among the three species. The CT of the rat EDL, in spite of its higher proportion of type II B fibers about 10% was the same as that of the guinea-pig EDL. The SOL of the mouse, composed of about 50% type I (SO) fibers, had a CT about as short as that of the EDL. In the case of the classification by Peter et al., the relationship between the percentage of subgroups of fast-twitch fibers and the CT or 1/2 RT, but not the resistance to fatigue, was not obvious. The resistance to fatigue tended to be enhanced in proportion to the area occupied by FOG in the EDL and by SO (type I) in the SOL. These results suggest that the contractile properties of individual fibers identified histochemically are distinct among animal species, producing interspecies differences in fiber types along with different contractile properties. However, it may be possible to compare the difference between fiber types and CT or 1/2 RT in the classification based on the pH lability of myosin ATPase, and also the difference between fiber types and resistance to fatigue in the classification based on the oxidative enzyme.
...
PMID:[Fiber types and some contractile properties of extensor digitorum longus and soleus muscles in different animal species]. 183 29

This study was designed to determine the effects of reduced neuromuscular activity on the expression of proteins associated with contractile and metabolic functions and the size of single muscle fibers in the cat soleus. Adult cats were spinalized (Sp) at T12-T13 and maintained in a healthy condition for 6 months. Some of the cats were trained to weight-support (Sp-WS) for 30 minutes per day beginning one month posttransection. Cross-sectional area (CSA), succinate dehydrogenase (SDH), alpha-glycerophosphate dehydrogenase (GPD), and myofibrillar adenosine triphosphatase (ATPase) activities were determined in a population of single fibers identified in frozen serial cross-sections. Each fiber was categorized as either light or dark based on its staining density for qualitative myosin ATPase, alkaline preincubation (pH 8.75). The Sp (45%) and Sp-WS (31%) groups had significantly higher percentages of dark ATPase fibers than control (less than 1%). All dark ATPase fibers were shown to react positively for a fast myosin heavy chain monoclonal antibody, while some of these fibers showed a reaction to both fast and slow myosin heavy chain antibodies. Overall mean fiber CSA were significantly smaller (approximately 25%) than control in both Sp groups. In the Sp-WS, but not the Sp cats, the dark fibers were larger than the light fibers (P less than 0.05), suggesting a preferential effect of postural training on the ATPase converted fibers. There were no significant differences among the three groups in any of the mean enzyme activities for either ATPase type fiber. However, there was a general tendency for the Sp cats to have elevated GPD and ATP activities per muscle; this appeared to be directly related to the percentage of fibers staining darkly for myosin ATPase. These data indicate that 6 months after spinalization some of the fibers of the slow muscle developed fast myosin staining patterns and oxidative and glycolytic enzyme profiles that are normally exhibited in fast fatigue-resistant motor units. Periods of daily weight-support appear to ameliorate some of these adaptations to spinalization. Further, the observation that SDH activities are maintained at control values in spinalized adult cats as well as in spinalized kittens (unpublished observations) suggest that, at least in the soleus, skeletal muscle fibers can maintain their oxidative potential even though there is a marked reduction in neuromuscular activity for 6 months.
...
PMID:Expression of a fast fiber enzyme profile in the cat soleus after spinalization. 214 97

Postoperative pulmonary complication and respiratory failure, frequently seen in undernourished patients such as those with esophageal cancer, were suspected to be due to respiratory muscle wasting caused by nutritional depletion. Based on this idea, the respiratory muscles obtained by biopsies during operation from diaphragm, external intercostal muscle, and rectus abdominis muscle were assessed histochemically in 32 patients. The specimens were stained for myosin ATPase to differentiate the types of muscle fibers, and then the size and distribution of the muscle fibers of each type were measured. In diaphragm muscle, cross-sectional areas of type 1 & 2 and the ratio of the area occupied by each fiber were usually the same; in external intercostal muscle, however, type 1 fibers were dominant and in rectus abdominis muscle, type 2 fibers were dominant. The cross-sectional area of each respiratory muscle fiber well correlated with certain anthropometrical indexes, and the nutritionally depleted cases, the muscle fibers were of a smaller size suggesting less respiratory muscle strength. The ratio of the area occupied by type 1 fibers in diaphragm muscle was linearly related to serum albumin, total cholesterol, and PNI (prognostic nutritional index). Type 2 fibers were dominant in malnourished patients, suggesting greater fatigue compared to well-nourished cases. Opposite findings were obtained in external intercostal muscle and rectus abdominis muscle, and the ratio of the area occupied by type 2 fibers was smaller in the undernourished cases, suggesting reduced maximum strength of these muscles.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:[Histochemical analysis of respiratory muscles of patients with esophageal cancer--with special reference to the preoperative nutritional state]. 214 8

The studies describe alterations after hypophysectomy in the proportion of the type-1 and type-2 fibres in rat skeletal muscles, and the effects of replacement treatment with pituitary human (h) GH. Cytochemical analysis of myosin ATPase, succinate dehydrogenase and lactate dehydrogenase activities in sections of rat hind limb muscles were used as markers of fibre type and revealed that hypophysectomy reduced the proportion of type-1 fibres by 50% in soleus and in extensor digitorum longus muscles. This reduction in the proportion of type-1 fibres was accompanied by the appearance of transitional fibres (type 2C/1B). Following seven daily injections of hGH (60 mIU/day) to hypophysectomized rats, the proportion of type-1 fibres in both soleus and in extensor digitorum longus was increased with a concomitant reduction in the number of transitional fibres. After 11 days of treatment, all these transitional fibres had reverted back to type-1 fibres. Only hGH was observed to elicit this effect; injections of other pituitary hormones had no effect on the proportions of these transitional fibres. These alterations in fibre type occurred more rapidly than the changes reported after prolonged electrical stimulation of muscle or following extended exercise. These findings suggest that hypophysectomy and GH injection can result in a rapid alteration in the fibre composition of skeletal muscle, which may have important implications in terms of the resistance to fatigue and speed of contraction of the muscle.
...
PMID:Human growth hormone treatment of hypophysectomized rats increases the proportion of type-1 fibres in skeletal muscle. 253 79

Corticosteroids have been shown to produce a myopathy of peripheral skeletal muscle, characterized predominantly by Type II fiber atrophy. To determine if similar histologic and histochemical changes occur in the diaphragm and whether the in vitro contractile properties of this muscle are adversely affected by steroids, we studied two groups of hamsters. The experimental group received triamcinolone while a control group received saline, both given daily for 3 wk as i.m. injections. Soleus (Sol) and extensor digitorum longus (EDL) muscles and costal diaphragm muscle sections were stained for histologic (hematoxylin and eosin, modified Gomori trichrome) and histochemical (myosin ATPase, succinate dehydrogenase [SDH]) analysis. Muscle fiber proportions and cross-sectional areas (CSA) were measured from myosin ATPase sections. In vitro studies of isometric contractions were carried out on small strips of costal diaphragm, measuring maximal isometric twitch (Pt) and tetanus (Po) tensions, time to peak tension (TTP), half relaxation time (1/2 RT), force-frequency relationship, and fatigue characteristics (60 Hz tetani; duty cycle, 0.5). Triamcinolone treatment resulted in no change in muscle fiber proportions. There was no effect on Type I fiber CSA; however, there was Type IIa (Sol, EDL) and Type IIb (diaphragm, EDL) fiber atrophy in triamcinolone-treated animals. Pt and Po (normalized for weight) of diaphragm strips were not different. There was a prolongation in TTP and 1/2 RT, a left shift in the force-frequency curve, and a reduced fatiguability of triamcinolone-treated diaphragm (P less than 0.05). We conclude that a steroid myopathy could be explained by a loss of muscle mass (Type IIb fiber atrophy) rather than an intrinsic impairment in contractile function.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Pathologic changes and contractile properties of the diaphragm in corticosteroid myopathy in hamsters: comparison to peripheral muscle. 262 59

The succinate dehydrogenase (SDH) activity and cross-sectional area of individual muscle fibers in the cat diaphragm were quantified using a computerized image-processing system. The population distributions of fiber-SDH activities and cross-sectional areas showed considerable range within each diaphragm. Despite an overlap in the distribution of SDH activities between fast-twitch (i.e., those staining darkly for myosin ATPase) and slow-twitch (i.e., those staining lightly for myosin ATPase) fibers, differences between the two populations of fibers were observed. Fast-twitch fibers generally had lower SDH activities and greater cross-sectional areas than slow-twitch fibers. However, the range of SDH activities and cross-sectional areas of fast-twitch fibers was much greater than in slow-twitch fibers. The population distributions of SDH activities and cross-sectional areas of both fast- and slow-twitch fibers were unimodal. The unimodal distribution of SDH activities in fast-twitch fibers suggested that these fibers could not be clearly subdivided into two groups based on differences in their oxidative capacity (i.e., high- and low-oxidative fibers). These results were discussed in the context of the classification of fast-twitch glycolytic and fast-twitch oxidative-glycolytic fibers using qualitative histochemistry. In addition, the functional significance of the unimodal distribution of oxidative capacities in fast-twitch fibers was discussed in relation to the distribution of fatigue properties in fast-twitch motor units. A significant negative correlation between cross-sectional area and SDH activity in both fast- and slow-twitch fibers was also observed. The importance of this negative correlation in relationship to the diffusion of energy substrates for oxidative metabolism was discussed.
...
PMID:SDH activity and cross-sectional area of muscle fibers in cat diaphragm. 293 51

The effects of endurance training on the histochemical and contractile properties of developing rat soleus was studied. Five 18 day old Long Evans rats were trained twice a day for 28 days (E group); workloads were increased to 30 m/min (15% grade) for 40 min/bout. Contraction time (Tc), twitch tension (Pt), half relaxation time (t1/2R), tetanic tension (Po), maximal rate of rise in tension (t50% Po) and fatigue index (FI, % decline in force after 15 s tetanic stimulation) were measured and compared to a control (C) group. The contralateral soleus was excised, rapidly frozen and histochemical (myosin ATPase pH 9.4 and 4.3) and histological sections prepared for analysis of fibre type, number and area. Similar fibre types (mean = 70 and 71% ST), fibre numbers (mean = 2115 and 2242) and areas of ST (mean = 2000 and 2320 micron 2) and FT fibres (mean = 1476 and 1628 micron 2) were found in C and E groups respectively. Po (p less than 0.05) was greater and t50% Po (p less than 0.01) was significantly faster in E. Pathological changes were found in about 1% of fibres in each trained muscle, but not in controls. Histochemical differentiation of fibre types was unaffected and contractile properties only minimally by training during early development.
...
PMID:Histochemical and contractile properties of soleus muscle trained during development. 294 70


1 2 3 Next >>

---