Browsing by Subject "Muscle fibre types"

Now showing 1 - 4 of 4
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    Degree of correspondence between contractile and oxidative capacities in horse muscle fibre, a histochemical study
    (Murcia : F. Hernández, 1990) López-Rivero, J.L.; Agüera, E.; Rodríguez Barbudo, M. V.; Galisteo, A. M.; Morales-López, J. L.
    Samples taken from the middle gluteal muscle of 95 untrained adult horses of different ages and sex were subjected to histochemical analysis using the myosin adenosine triphosphatase (m-ATPase) and nicotinamide adenine dinucleotide tetrazolium reductase (NADH-TR) staining techniques. Fibres were classified into types 1, IIA and IIB according to m-ATPase activity after preincubation at pH 4.4. The percentage of FT (Fast-Twitch Glycolytic) fibres and the proportion of IIB fibres with «high» and «low» oxidative capacity were determined in serial sections stained for NADH-TR. Statistical analysis revealed a significantly higher proportion of IIR fibres than FT fibres (P < 0.001), though both percentages were correlated. Thus, 72.2 +/- 17.6% of type IIB fibres showed low oxidative capacity , but the remaining 27.8 +/- 17.6% showed high aerobic potential, and thus did not correspond to FT fibres. These results confirm that the contractile capacity of a muscle fibre does not determine its oxidative profile. The different types of muscle fibre should thus be classified solely according to m-ATPase activity, since this characteristic is related to the molecular structure of contractile proteins. Oxidative capacity should be assessed separately, and not be used as a criterion for fibre classification in horses.
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    Skeletal muscle abnormalities associated with occupational exposure to mercury vapours
    (Murcia : F. Hernández, 2000) Nadorfy-Lopez, E.; Torres, S.H.; Finol, H.; Mendez, M.; Bello, B.
    There is scarce information on the possible effects of chronic exposure to mercury on skeletal muscle. Dental personnel are frequently exposed to inhalation of metallic mercury vapours. The skeletal muscle of five technicians and one dentist (females, age 36-55) was studied. All of them presented symptoms of chronic mercury poisoning. Needle biopsy was taken from the quadriceps femoris muscle and samples were prepared for light microscope histochemistry and for transmission electron microscopy. Selective atrophy of type IIB muscle fibres was found in patients, and in one of them there was fibre grouping. Most of the muscles showed increased fibre area per capillary. Atrophy was confirmed by the ultrastructural study, demonstrating increase of intermyofibrillar spaces, loss of myofibrils or complete disappearance in some fibres, and sarcolemmal folding. Splitting of the fibres was also found. Some capillaries were altered, showing endothelial infoldings into the lumen, thickened basement membrane and partial or total occlusion. The alterations found in muscle may be secondary to nerve damage, to ischemia caused by capillary lesion andlor to a direct effect of mercury on muscle fibre proteins.
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    Type IIC fibres in certain muscles of the adult rat (sedentary and exercised)
    (Murcia : F. Hernández, 1990) Morales-López, J. L.; Agüera, E.; Vivo, J.; López-Rivero, J.L.
    Samples were taken, at fixed levels, of the vastus lateralis, the caput lateralis of the gastrocnemius muscle and the longissimus lumbaris of 72 Wistar rats which were either sedentary or subjected to various exercise schedules. The samples were analyzed using the histochemical technique of myosin ATPase (m-ATPase) after preincubation at pH 4.2, and the fibre-types I, I1 (IIA and IIB) and IIC were identified, calculating the percentage of type IIC fibres as well as their minimum diameter. The percentages of these IIC fibres found in the red and mixed parts of the gastrocnemius (caput lateralis) and the longissimus lumbaris were between 0.7% and 2.6%. However, their presence was not detected in the vastus lateralis or in the white part of the gastrocnemius (caput lateralis). The lack of differences in this fibre type between the males and females of the population was shown statistically. Likewise, no significant modification of the IIC fibres between sedentary and exercised animals was seen. With regard to fibrillar size, females showed a smaller minimum diameter than males, the results showing a small increase in the size of these fibres in both sexes after exercise, although in most cases this was not statistically significant.
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    Variations in fibre composition of the gastrocnemius muscle in rats subjected to speed training
    (Murcia : F. Hernández, 1990) Morales-López, J. L.; Agüera, E.; Miró, F.; Diz, A.
    Thirty-six adult Wistar rats were divided into three groups. One group was used as a control, and the other two underwent different training programmes in which greater relevance was attached to the intensity of exercise than to its duration. Samples of the red and mixed portions of m. gastrocnemius (caputlateralis) were stained with m-ATPase to determine the percentage of type 1, IIA and IIB fibres, and with NADH-TR in order to quantify variations in the percentage of low staining intensity (FG) fibres. The most notable results obtained were: a) the ratio of type 1 type 11 fibres remained unchanged; b) the proportion of IIA fibres increased, while that of IIB fibres decreased correspondingly; c) FG fibres, which were virtually absent from the red portion, recorded a clear decrease which was more marked, and occurred more rapidly, than in IIB fibres. These differences were al1 statistically significant in the mixed portion of the muscle. Adaptative changes in fibre composition in the red portion were less marked.