Stretch receptors in the eye muscles of a teleost fish

Summary Extraocular muscles of a teleost fish,Girella tricuspidata, contain a predominantly phasic stretch receptor, which consists of fine beaded nerve terminals within the red portion of the muscle.The authors are grateful to Mr V. Straznik for supplying the fish, and to Mrs M. Fisher for histological assistance. Financial support for this work was received from the New Zealand Medical Research Council and the Auckland University Research Committee and University Grants Committee.     

Protein bound calcium in piscine red and white muscles

Summary The levels of Ca⁺⁺ and calcium binding properties of sarcoplasmic proteins in red and white muscles of cat fish were compared. The white muscle is characterized by greater water content, ionic calcium and Ca-binding capacity, whereas the red muscle is characterized by a higher calcium sensitive protein content.The authors are grateful to Dr R. Narayana, Director of Instruction (BS & H), University of Agricultural Sciences, Bangalore for facilities and encouragement.     

Conduction,automaticity, and tonus of visceral muscles

Résumé Les muscles lisses des Vertébrés appartiennent à deux catégories: ceux des viscères, lesquels ont une fonction automatique, et ceux qui comme les muscles des vaisseaux sanguins sont innervés par les nerfs moteurs. Les propriétés physiologiques des muscles lisses viscéraux sont très semblables à celles du muscle cardiaque ainsi que l'a montré l'étude de la conduction, du potentiel d'action et des effets du courant électrique. Les particularités des muscles lisses viscéraux tiennent en grande partie à la lenteur de leur réaction et aux fluctuations que présente leur excitabilité. Cette dernière est influencée par des facteurs tels que des hormones, des excitations transmises par les nerfs extrinsèques et, dans le cas de l'intestin, par le système nerveux intrinsèque. Les contractions spontanées débutent par une activité locale qui augmente lentement et se manifeste par un changement du potentiel et un accroissement du «tonus». Le tonus se produit dans les muscles lisses par diverses modifications de l'état physiologique. Rien ne prouve qu'il soit provoqué par un mécanisme essentiellement différent de celui des contractions rapides.     

Collagen in aging muscles.

The salt, acid and insoluble collagen fractions were estimated in red, white and cardiac muscles of 10-, 15- and 20-month-old albino rats. The total collagen level with reference to total proteins is more in red than in white and cardiac muscle. Accumulation of more of insoluble collagen and decrease in salt extractable collagen is seen in all three muscles with aging.     

Spirally arranged muscles associated with tracheoles in tsetse fly flight muscles; their possible involvement in sound production

Summary A set of muscle fibres have been found associated with certain tracheoles in the flight muscles of the tsetse fly. It is proposed that those muscles may be involved in sound production in the fly.I am grateful to the Ministry of Overseas Development for a grant in support of this work and to Professor L.H. Finlayson for his advice and criticism.     

Myosin isoenzymes during in vivo and in vitro differentiation of chick muscles

Muscle fibers differentiated, in vitro, from myoblasts of embryonic Pectoralis (presumptive fast) and embryonic Adductor magnus (presumptive slow) muscles synthesise the same type of myosin, which is identical to the type synthesised in day 10 embryonic muscles. This type of myosin comigrates with the third isozyme of the adult fast-twitch muscle. There is no change in the kind of myosin in cultures aged from 2 to 7 weeks, whereas during the in vivo differentiation of the same muscles, new isozymes appear which are different in the two muscles. With regard to myosin, the muscle fibers differentiated, in vitro, from myoblasts of fast or slow muscles expressed the same phenotype.     

Histochemistry of some trout respiratory muscles

Summary A histochemical study has been made of the main cranial muscles which produce ventilation movements of the rainbow trout. It is shown that a greater proportion of red(aerobic) fibres is present in those muscles known to be active during shallow ventilation than those which become active at greater ventilation volumes. An ordered recruitment of red, pink and white fibres within these muscles is also likely.This work was carried out when I.A. Johnston was holding an NERC Post-Doctoral Research Fellowship (1973–75).     

Histochemistry of some trout respiratory muscles.

A histochemical study has been made of the main cranial muscles which produce ventilation movements of the rainbow trout. It is shown that a greater proportion of red(aerobic) fibres is present in those muscles known to be active during shallow ventilation than those which become active at greater ventilation volumes. An ordered recruitment of red, pink and white fibres within these muscles is also likely.     

The content of citrate in resting muscles from vertebrates and invertebrates

Summary There is a marked difference between the content of citrate of anaerobic and aerobic muscles. The variation of the citrate content in insect flight muscles is very small.     

Difference in the sensitivity to Ca ion among glycerinated skeletal, cardiac and smooth muscles

Glycerinated smooth muscle was contracted almost maximally with 15 mM Mg and 5 mM ATP, while extracted skeletal and cardiac muscles needed Ca ion with 15 mM Mg and 5 mM ATP for producing contraction.     

Nerves and muscles regulating feather follicle movements in the chicken

Summary It was found that most feather follicles possess more than a single muscle system but only single nerve endings were observed in a feather follicle. It seems that muscles exist which antagonize each other. Anastomoses of nerves orginating from different sources and flowing of mixed nerves into the feather follicle could explain the antagonistic action of the muscles on the feather follicle.Partially supported by a grant from the Israel Egg and Poultry Board.     

Dystrophin-dependent efficiency of metabolic pathways in mouse skeletal muscles

Muscles from themdx mouse (X-linked genetic disorder similar to Duchenne muscular dystrophy) lack dystrophin-associated transsarcolemmal proteins¹ and show reduced maintenance metabolic rates². Here, microcalorimetric comparisons of metabolic stimulation by exogenous substrates in isolated muscles revealed substrate-selective limitation of chemical reaction rates through both glycolytic and TCA-cycle pathways, identical in slow- and fast-twitchmdx muscles. This systemic approach, as opposed to comparisons of single-enzyme activities, sheds new light on the function of dystrophin and associated proteins. The in vivo efficiency of metabolic pathways may depend on stabilization of enzyme complexes by dystrophin-associated elements of the cytoskeleton.     

Electron spin resonance spectra of white,cardiac and various red skeletal muscles of the carp,Cyprinus carpio L

Résumé Les mesures de résonance paramagnétique électronique effectuées jusqu' à présent sur le muscle n'ont pas tenu compte de la différentiation de ce tissu en muscles blancs et rouges. Nous avons comparé les signaux du muscle blanc, du muscle cardiaque et de divers muscles rouges de carpe. Le muscle blanc présente une très faible intensité; le myocarde et différents muscles rouges donnent des valeurs plus élevées en accord avec leur plus grande teneur en mitochondries. Le muscle rouge de la ligne latérale se distingue toutefois des autres muscles rouges par un signal environ 2×plus intense dû, comme le montrent des examens histologiques, à la présence dans ce cas de mélanocytes situés le long de faisceaux conjonctifs et de capillaires sanguins.     

Difference in the sensitivity to Ca ion among glycerinated skeletal,cardiac and smooth muscles

Summary Glycerinated smooth muscle was contracted almost maximally with 15 mM Mg and 5 mM ATP, while extracted skeletal and cardiac muscles needed Ca ion with 15 mM Mg and 5 mM ATP for producing contraction.Acknowledgments. I thank Prof. T. Suzuki and Dr H. Nakanishi for helpful suggestions, and Mr G. Ito for technical assistance.     

Biochemical efficiency and intrinsic shortening speed in selected vertebrate fast and slow muscles

Summary The biochemical efficiency was measured in iodoacetate N₂ and NaCN-treated muscles by dividing the work done by the amount of phosphoryl creatine hydrolysed when contracting at their optimum velocity. An inverse relationship was found between the intrinsic speed of shortening (V_max) of the muscles and their mechanochemical efficiency.     

Increased susceptibility to lipid peroxidation in skeletal muscles of dystrophic hamsters

Summary The results showed that the total content of lipids, which could be peroxidized with Fe(2+)/ascorbate stimulation in vitro, was 45.4% and 53.7% higher than normal in the dystrophic hamster muscle at the age of 1 and 3 months, respectively. Correspondingly, the susceptibility to lipid peroxidation (stimulated by ADP-chelated iron at 37°C) was 38.6–74.3% higher in dystrophic muscles. The increases were not related to necrotic lesions and inflammation observed. The activities of glucose-6-phosphate dehydrogenase, glutathione reductase, thioredoxin reductase and catalase were increased in dystrophic muscles but those of superoxide dismutases and glutathione peroxidase were unaffected.     

Increased susceptibility to lipid peroxidation in skeletal muscles of dystrophic hamsters

The results showed that the total content of lipids, which could be peroxidized with Fe(2 +)/ascorbate stimulation in vitro, was 45.4% and 53.7% higher than normal in the dystrophic hamster muscle at the age of 1 and 3 months, respectively. Correspondingly, the susceptibility to lipid peroxidation (stimulated by ADP-chelated iron at 37 degrees C) was 38.6-74.3% higher in dystrophic muscles. The increases were not related to necrotic lesions and inflammation observed. The activities of glucose-6-phosphate dehydrogenase, glutathione reductase, thioredoxin reductase and catalase were increased in dystrophic muscles but those of superoxide dismutases and glutathione peroxidase were unaffected.     

Uptake and transport of exogenous peroxidase in the masticatory muscles of cats. Localization of ganglionic neurons]

Retrograde axonal transport of Horseradish peroxydase (HRP) has been used to trace the cells of origin of proprioceptive fibers in jaw-closing and jaw-opening muscles. After injection of HRP in young cats' masticatory muscles (masseteric, temporal, pterygoid, mylohyoid and digastric) labelled neurons were found in the ipsilateral semi-lunar ganglion and trigeminal mesencephalic nucleus. It is concluded that sensory endings are present in jaw-opening as in jaw-closing muscles; possibly the afferent fibers from muscle endings of the opener muscles have their somata in the mesencephalic nucleus, afferent fibers from tendinous receptors in the semi-lunar ganglion.     

The effect of exercise on protein turnover in isolated soleus and extensor digitorum longus muscles

The rate of protein degradation was found to be increased in isolated soleus and extensor digitorum muscles of 60-80 g rats after exercise consisting of running for 120 min. These findings support the hypothesis that exercise causes an increase in skeletal muscle protein degradation, and that both red and white muscles are affected similarly.     

A light microscope study of fibre diameter and sarcomere length relationships in rigor skeletal muscles

Summary Correlation coefficients between fibre diameter and sarcomere length were significant in relaxed, unfixed muscles in rigor, indicating that fibres with large diameters had short sarcomeres and fibres with small diameters had long sarcomeres. No significant correlations were obtained in muscles from limbs that entered rigor in a folded or stretched position.