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Biomedical subjects

G Goldspink

Publications and source records attributed to G Goldspink.

At least 109 records · Page 6Linked to original sources
PubMed1982

Exercise-induced morphological and biochemical changes in skeletal muscles of the rat.

Morphological and biochemical changes have been studied in two forelimb (i.e., brachialis and extensor carpi radialis) and two hindlimb (i.e., soleus and extensor digitorum longus) muscles of rats subjected to short bursts of high-intensity exercise over 2 wk. Regardless of muscle type, all four muscles grew significantly, accumulating protein, RNA, and DNA at faster rates than in the growing control tissues. Of the intrinsic fiber types within the individual muscles all increased their cross-sectional areas, but the fast-oxidative, glycolytic fibers (type IIa) showed marginally more hypertrophy than the slow-oxidative (I) or fast-glycolytic fibers (IIb). Induced changes in protein turnover were consistent with the additional growth of the exercised muscles. However, the precise alterations in the rates of protein synthesis and protein breakdown varied according to the fiber type composition of the muscle. The increased growth rate of the two principally fast-twitch muscles (i.e., brachialis and extensor digitorum longus) correlated solely with an enhancement of protein synthesis (measured in vivo). In contrast, the hypertrophy of the slow-twitch soleus appeared to relate only to a decrease in protein breakdown (a calculated value). In a more intermediate type of muscle (i.e., extensor carpi radialis) a complementary combination of an increase in synthesis and a decrease in breakdown was found.

Animals↗
PubMed1981

Connective tissue changes in surgically overloaded muscle.

The effects of overload on the connective tissue component of the soleus muscle of the rat have been investigated. Three weeks after tenotomy of its synergistic muscles the soleus underwent considerable increase in weight. This was shown to have resulted from an increase in size of the predominant fibre type. Whilst occasional groups of fibres appeared to have resulted from the splitting of large single fibres, there was not significant increase in the number of fibres in cross-section of the muscle belly. The connective tissue content of the overloaded muscles was investigated using both histological and biochemical techniques. It was found that muscle fibre hypertrophy was accompanied by an increase in the connective tissue component. Furthermore, there was an increase in the proportion of collagen to muscle fibre tissue.

Animals↗
PubMed1980

Bursting pressure and collagen content of fetal membranes and their relation to premature rupture of the membranes.

The collagen content and the bursting pressure of human fetal membranes was measured for full term spontaneously ruptured, full term artificially ruptured and prematurely ruptured membranes. The bursting pressure of the prematurely ruptured membranes was significantly higher than the membranes which ruptured spontaneously at term. No significant difference was found in the collagen contents.

Collagen↗
PubMed1979

Changes in rodent muscle fibre types during post-natal growth, undernutrition and exercise.

1. Using histochemical staining methods for myosin ATPase oxidative and glycolytic enzymes, three major types of muscle fibre could be identified in the skeletal muscle of hamsters and mice. 2. Muscle fibre counts showed that the proportions of the different fibres were not entirely stable with age. In the hamster biceps brachii which is predominantly composed of ATPase-high fibres there was a decrease in the number of ATPase-low fibres. In the soleus muscle which is predominantly composed of ATPase-low fibres there was a decrease in ATPase-high fibres with age. 3. Although there was a change in the proportions of fibre types there was no change in the total number of fibres within the muscles with age. It is suggested that some reinnervation may take place during growth and that this is why the less dedominant fibre type decreases. 4. The response of the different fibre types to partial starvation was studied. The ATPase-high fibres showed the greatest decrease in size. Of these, the ATPase-high glycolytic type responded more than the ATPase-high oxidative type. The effects of the under-nutrition on the different fibre types were found to be completely reversible. Starvation did not affect the total number of fibres or the numbers of any fibre type. 5. The response of the different types to high intensity exercise (weight lifting) was studied. This type of exercise resulted in hypertrophy of all three major fibre types. However, the extent of the response varied according to the fibre type and the exact nature of the exercise. In most cases the ATPase-high fibres underwent hypertrophy more readily than the ATPase-low fibres. Where distinction was made between the two types of ATPase-high fibres, the ATPase-high glycolytic were found to hypertrophy more than the ATPase-high oxidative fibres. The effects of post exercise recovery (return to relative inactivity) were also studied and the changes in size of the fibres were found to be completely reversible.

Adenosine Triphosphatases↗
PubMed1979

Fibre number and fibre size in a surgically overloaded muscle.

Soleus muscles of male and female mice were overloaded by surgical resection of parts of gastrocnemius and plantaris. The effects of overloading were examined histologically after 7, 55 and 208 post-operative days, and also in teased preparations. Animals studied after 7 post-operative days showed a marked increase in muscle weight, but no significant change in mean fibre diameter or fibre number. Animals studied after 55 and 208 post-operative days showed an increase in soleus muscle weight, with fibre hypertrophy (but no increase in fibre number) proximally, while distally there was an increase in the number of fibre profiles in cross sections, some being wider, some thinner than normal. The small diametered fibres seem to persist indefinitely. From the evidence, both direct and indirect, it was concluded that surgically overloaded fibres split longitudinally into unequal parts, and that this explains the increase in fibre profiles in distal cross sections as well as their variation in size. It is clear that, because of the splitting, a surgically overloaded muscle is a difficult model on which to study fibre hypertrophy.

Animals↗
PubMed1978

A combined histochemical and biochemical study of myofibrillar ATPase in pectoral, leg and cardiac muscle of several species of bird.

Frozen sections of the pectoral, gastrocnemius and cardiac muscles from seven different species of birds were stained for myofibrillar ATPase and for succinic dehydrogenase. Several methods of myofibrillar ATPase were used including different pre-incubation treatments. Myofibrillar ATPases were also measured biochemically and the pH profile of the activity was compared with the histochemical staining following pre-incubation at different pH. Myofibrils from the different muscles were also subjected to sodium dodecyl sulphate acrylamide gel electrophoresis in order to separate the low molecular weight components of myosin. The results demonstrated that histochemical methods can be applied, with a reasonable degree of confidence, to classifying fibres in avian muscles although the classification used for mammalian muscles needs to be modified. They also showed that avian muscles, particularly the pectoralis, varies considerably between species and their mode of locomotion.

Adenosine Triphosphatases↗
PubMed1978

The effect of training on the swimming muscles of the goldfish (Carassius auratus).

Goldfish (Carassius auratus) were exercised continuously for periods of 28 days at swimming speeds of 1.5, 3.0 and 4.5 body lengths per second and their rates of growth were determined. Changes in muscle fibre size were examined, as were changes which occurred in the concentrations of the major chemical constituents of these cells. These fish, typical of the carp family in that they are found only in still or slowly moving water, did not adapt well to the flowing water environment at any swimming speed. They often grew less than the controls, although consuming much more food. Changes in the composition of the muscle fibres indicated that excess food was not being stored, and also indicated that the major fuel for swimming at all speeds was glycogen. The fish survived well at high speeds and it was suggested that this was due to the ability of the species to metabolize glycogen anaerobically without the production of lactic acid.

Animals↗
PubMed1977

Further studies on the adaptation of fish myofibrillar ATPases to different cell temperatures.

Previous studies on fish Mg2+Ca2+ activated myofibrillar ATPases have been extended to species inhabiting diverse thermal environments. Cold adapted ATPases have considerably higher catalytic centred activities at low temperatures than warm adapted ATPases. Differences in cell temperature have also lead to evolutionary modifications in thermodynamic activation parameters. The free energies (deltaG2+), enthalpies (deltaH2+) and entropies (deltaS2+) of activation of the Mg2+Ca2+ myofibrillar ATPase are positively correlated with adaptation temperature. Myofibrils with CaATP-2 as substrate in the absence of Mg2+ will hydrolyse ATP by a mechanism not associated with fibril shortening. Differences in activation enthalpies (deltaHH) between cold and warm adapted Ca2+-activated myofibrillar ATPases are less pronounced than for the physiological ATPase. Furthermore the Ca2+-activated ATPase showed no relationship between environmental temperature and substrate turnover number or free energy of activation (deltaG2+).

Acclimatization↗
PubMed1976

Mechanism of myofibril growth and proliferation in fish muscle.

The mechanisms of myofibril growth proliferation were investigated in the red and white muscles of fish. In both types of muscle the ratio of lattice filament spacings between the Z disk and M line was found to be greater than that required for perfect transformation of a square into a hexagonal lattice. This mismatch was considered to result in the thin filaments being pulled obliquely instead of at right angles to the Z disk. The angle of pull of the thin filaments was measured in longitudinal sections. The splitting process was found to decrease the degree of pull. Splitting was also observed in transverse sections of the peripheral myofibrils. In both red and white fibres these myofibrils were found to commence splitting when they reached a size of approximately 1-2 mum diameter. Evidence from ultrastructural and autoradiographical studies suggested that growth of the myofibrils within the fibres is centrifugal. The outermost myofibrils appear to be the ones which are being built up and which split. The data indicated that in fish muscle a considerable number of filaments may be added to the daughter regions whilst splitting of the myofibril is still continuing.

Animals↗
PubMed1976

The effect of denervation and dystrophy on the adaptation of sarcomere number to the functional length of the muscle in young and adult mice.

In young animals the elongation of the limb bones increases the functional lengths of the muscles. In adult animals the functional length of a muscle can be increased by immobilizing it in the lengthened position. In both cases the muscle adapts by adding on more sarcomeres in series. The role of the nerve supply in this adaptation has been investigated using denervated muscles and muscles from dystrophic animals where there is thought to be an abnormality of the nerve supply. Postnatal sarcomere addition in denervated muscles falls short of that of controls. Although this might mean that the nerve supply is necessary for normal addition of sarcomeres, it is just as likely that there is a change in gait resulting from denervation, which affects the sarcomere number. Sarcomere number in fully grown mice is not affected by denervation, nor is the ability of the muscle to adapt to immobilization in the lengthened position. This is true for fast-twitch as well as slow-twitch muscles. In dystrophic muscles postnatal sarcomere addition is normal, although the presence of a few short fibres in the muscle may mean that some muscle fibres cannot adapt to an increase in the functional length of the muscle accompanying bone growth. Adult dystrophic muscle is capable of adapting to immobilization in the lengthened position. However, although the total number of additional sarcomeres is the same as in normal immobilized muscle, they are added on at a slower rate. The experiments show that although denervated and dystrophic muscle fibres are in a state of atrophy they are still capable of adding on sarcomeres in series when the functional length of the muscle is increased. It would appear that the mechanism which enables the muscle to respond in this way to an increased functional length does not involve the nerve supply. This work was supported by a grant from the National Fund for Research into Crippling Diseases.

Age Factors↗