Changes in the acid phosphatase activity in skeletal muscles in temporary acute ischemia of the extremities and in early postischemic recirculation

Acid phosphatase (APh) activity has been experimentally studied on 69 dogs in the musculus soleus during ischemic and postischemic periods. Absence of an essential APh activation demonstrates a complete adaptation and stabilization of the intracellular mechanisms of homeostasis under an acute 3 hours' ischemia. Under a prolonged (6, 9, 12 h) ischemia APh activity in sarcoplasm of the muscle fibers increases considerably. This is, probably, one of the signs demonstrating structural-metabolic disadaptation and beginning of irreversible lesions. The data obtained make it possible to conclude that it is necessary to perform operative restoration of the blood stream in the extremities at early stages of ischemia.     

Morphological characteristics of changes in the skeletal muscle tissue of the extremities after experimental post-ischemic recirculation

The canine ischemic muscle tissue was subjected to a comprehensive morphological study after the recovery of the blood flow in the limbs for 2 hours. The effectiveness of of the recovery of the blood flow after the 3-hour ischemia was supported in acute experimental occlusion of the artery. The blood flow recovery after 6 hours of ischemia was associated with appreciable structural and metabolic abnormalities in the skeletal muscle fibers. These abnormalities were more demonstrable during recirculation after 9 and 12 hours of ischemia. No morphological criteria that might indicate whether the ischemic damage to the skeletal muscle is reversible or irreversible were defined. A comprehensive morphological study with an assay of structural and metabolic alterations is required instead.     

Morphological characteristics of the changes in the skeletal muscle tissue in acute experimental ischemia of the extremities

A comprehensive morphological study of the ischemic skeletal muscles of the limbs was performed in experiments on dogs. Ischemia of the muscle tissue was induced by artificial embolic occlusion of the terminal part of the aorta. A quantitative functional and morphological study revealed serious disturbances in metabolism of the skeletal muscle that was subjected to a 6-hour ischemia. Depression of aerobic metabolism, ineffectiveness of anaerobic glycolysis (a spare pathway of the synthesis of macroergic substances), a dramatic lowering of ATPase activity, and activation of acid phosphatase in experiments of such a duration are important signs of a probably compromised adaptation process and irreversibility of the lesions in the tissue. The data should be taken into consideration in determining the optimal periods of the blood flow recovery in the limbs. Morphological changes in muscle fibers under ischemia progress with an increase in the experiment duration (up to 9 and 12 h). An important morphological sign of ischemia is a disturbed typification of muscle fibers.     

Carbonic anhydrase isozyme distribution and characterization in metabolic fiber types of the dorsal levator muscle of the blue crab, Callinectes sapidus

Carbonic anhydrase (CA) distribution and characterization were examined in white and light pink fibers of the dorsal levator muscle of the blue crab. White fibers were structurally and metabolically characterized as fast twitch glycolytic, while the light pink fibers were fast oxidative. All subcellular fractions of both fiber types had significant levels of CA activity; cytoplasmic and microsomal activity was significantly higher in light pink vs white fibers. Cytoplasmic CA from both fiber types was highly sensitive to the inhibitors acetazolamide and chlorzolamide, with Ki values of approximately 2 and 0.4 nM, respectively. Further analysis confirmed that cytoplasmic CA from both fiber types was kinetically similar to the high turnover Type II isoform. It appears that the evolution of the CA Type III isoform, found in vertebrate red muscle, did not occur with the differentiation of metabolic fiber types in crustaceans. Membrane-associated CA, which was also kinetically similar to the Type II isoform, was 20-fold higher in light pink fibers, suggesting a physiological role in facilitated CO2 efflux from the muscle fiber during periods of prolonged maximal activity.     

An immunohistochemical study of the rat m. lumbricalis at different periods of ischemia after its allograft into the anterior chamber]

The ability of muscle fibers to survive the ischemic condition was examined. After 0 to 11 h of ischemia of the rat m. lumbricalis was transplanted to the anterior chamber of the rats eye. Using a morphological and immunohistochemical (monoclonal antibodies to heavy chain of the fast myosin, PAP-method) methods it was revealed that population of surviving muscle fibers reduced significantly beginning from 6 h of ischemia. After 9 h of ischemia there were no muscle fibers in the transplant but one could observe the new formed muscle tubules. It is concluded that up to 6 h the muscle fibers of m. lumbricalis ischemia still preserve the ability to recover.     

Structural reaction of skeletal muscle mitochondria to deep hypothermia in the experiment

The reaction of locomotor muscle mitochondria was studied in white rats during different periods of deep hypothermia. An acute exposure to cold produced substantial changes of the muscle cellular mitochondrial apparatus, such as matrix swelling, crysts destruction with a significant decrease in mitochondrial profiles on the periphery of muscle fibers. Destructive and degenerative mitochondrial lesions were greater in prolonged hypothermia and subsequent warming. Such structural reaction of locomotor muscle mitochondria could reveal a substantial insufficiency of the muscle cellular energy apparatus during experimental hypothermia.     

Capillary and fiber size interrelationships in regenerating rat soleus muscle after ischemia: a quantitative study.

The present study examines the influence of ischemia on the muscle fibers and capillarization in rats. Muscle ischemia was achieved by a pneumatic tourniquet at a pressure of 300 mm Hg for 2, 4 and 6 h (groups I, II and III, respectively) to the right hindlimb above the knee. Numerous regenerative fibers were seen at 4 and, especially, 8 and 12 days after ischemia in groups II and III. The quantitative data revealed a significant decrease in the size of muscle fibers (regenerative fibers) in ischemic skeletal muscle, with a concomitant increase in fiber density. The capillary to fiber ratio shows a decrease at 4, 8 and 12 days after ischemia in the three experimental groups: in group I because of a decrease in capillary density; in groups II and III because of an increase in fiber density with respect to capillary density.     

Morpho-functional changes in the muscles of the limbs and their microcirculatory bed in acute ischemia

On 26 mature dogs in a chronic experiment the character of compensatory-adaptive changes in muscles and their blood capillaries have been studied in dynamics of an acute ischemia of the extremity and at some stages of recirculation. After strangulation for two hours, thanks to joining in the compensatory-adaptive mechanisms, certain morphofunctional changes in the extremity tissues are revealed. As the duration of hypoxia increases (6-9 h), the destructive changes in the tissues become more severe. They are inherent in an acute hypoxia and accompanied with disaggregation and hydratation of cell membranes of endotheliocytes, with formation of vesicles and spherules, with increasing microclasmatosis, formation of myelin-like bodies, with destructive changes of organelles, with destruction of sarcoplasmic reticulum, with focal discoid necrosis, myocytolysis and sequestration of autolysis altered groups of muscle fibers. The data obtained serves as a base for elaboration of a pathogenically adequate surgical treatment of severe forms of an acute ischemia of extremities.     

Tissue-specific changes in protein synthesis associated with seasonal metabolic depression and recovery in the north temperate labrid, Tautogolabrus adspersus

The tissue-specific changes in protein synthesis were tracked in relation to the seasonal metabolic depression in cunner (Tautogolabrus adsperus). In vivo protein synthesis rate and total RNA content were determined in liver, white muscle, brain, heart, and gill during periods of normal activity before metabolic depression, entrance into and during winter dormancy, and during the recovery period. The decrease in water temperature from 8 degrees C to 4 degrees C was accompanied by a 55% depression of protein synthesis in liver, brain, and heart and a 66% depression in gill. Protein synthesis in white muscle fell below detectable levels at this temperature. The depression of protein synthesis is an active process (Q(10) = 6-21 between 8 degrees C and 4 degrees C) that occurs in advance of the behavioral and physiological depression at the whole animal level. Protein synthesis was maintained at these depressed levels in white muscle, brain, heart, and gill until water temperature returned to 4 degrees C in the spring. Liver underwent a hyperactivation in the synthesis of proteins at 0 degrees C, which may be linked to antifreeze production. During the recovery period, a hyperactivation of protein synthesis occurred in white muscle, which is suggestive of compensatory growth, as well as in heart and liver, which is considered to be linked to increased activity and feeding. Seasonal changes in total RNA content demonstrate the depression of protein synthesis with decreasing temperature to be closely associated with translational capacity, but the stimulation of protein synthesis during recovery appears to be associated with increased translational efficiency.     

Muscle activity pattern dependent pain development and alleviation

Muscle activity is for decades considered to provide health benefits irrespectively of the muscle activity pattern performed and whether it is during e.g. sports, transportation, or occupational work tasks. Accordingly, the international recommendations for public health-promoting physical activity do not distinguish between occupational and leisure time physical activity. However, in this body of literature, attention has not been paid to the extensive documentation on occupational physical activity imposing a risk of impairment of health – in particular musculoskeletal health in terms of muscle pain. Focusing on muscle activity patterns and musculoskeletal health it is pertinent to elucidate the more specific aspects regarding exposure profiles and body regional pain. Static sustained muscle contraction for prolonged periods often occurs in the neck/shoulder area during occupational tasks and may underlie muscle pain development in spite of rather low relative muscle load. Causal mechanisms include a stereotype recruitment of low threshold motor units (activating type 1 muscle fibers) characterized by a lack of temporal as well as spatial variation in recruitment. In contrast during physical activities at leisure and sport the motor recruitment patterns are more dynamic including regularly relatively high muscle forces – also activating type 2 muscles fibers – as well as periods of full relaxation even of the type 1 muscle fibers. Such activity is unrelated to muscle pain development if adequate recovery is granted. However, delayed muscle soreness may develop following intensive eccentric muscle activity (e.g. down-hill skiing) with peak pain levels in thigh muscles 1–2 days after the exercise bout and a total recovery within 1 week. This acute pain profile is in contrast to the chronic muscle pain profile related to repetitive monotonous work tasks. The painful muscles show adverse functional, morphological, hormonal, as well as metabolic characteristics. Of note is that intensive muscle strength training actually may rehabilitate painful muscles, which has recently been repeatedly proven in randomized controlled trials. With training the maximal muscle activation and strength can be shown to recover, and consequently allow for decreased relative muscle load during occupational repetitive work tasks. Exercise training induces adaptation of metabolic and stress-related mRNA and protein responses in the painful muscles, which is in contrast to the responses evoked during repetitive work tasks per se.     

Morphofunctional characteristics of enzyme activity of the muscles in ontogenesis and after physical load

By means of histochemical methods using cytospectrophotometer in femoral muscles of white rats 1-, 3- and 12-month-old enzymatic activity of anaerobic and aerobic cycles has been estimated. The greatest changes occur after 20 days of physical load in 1- and 12-month-old animals. The semitendinous muscle (ventral origin), consisting mainly of red muscle fibers, works chiefly in aerobic regime and possesses a more manifested succinate dehydrogenase activity, and the quadriceps muscle (dorsal origin) consists principally of white fibers and its lactate dehydrogenase activity changes more noticeably.     

Modelling swimming activities and energetic costs in European sea bass (Dicentrarchus labrax L., 1758) during critical swimming tests

Muscular activity patterns in red and white muscles linked to oxygen consumption were studied during critical swimming tests in the sea bass (Dicentrarchus labrax Linnaeus 1758). The species is one of the most important for Mediterranean Sea aquaculture. A sigmoid model was used to fit both the oxygen consumption and red muscle activity while the white muscle activity pattern was described by an exponential model. Red muscle reaches an activation plateau close to critical swimming speed mostly due to the oxygen diffusion velocity in tissues. The exponential activation of white muscle appears to be linked to short and sudden periods of great energy need to cope with adverse conditions such as predation and escape. Both oxygen consumption and muscular activity were found to be size dependent. The bioenergetics of sea bass was modelled based on fish mass and swimming speed to predict the minimum and maximum speed as well as the mass-specific active metabolic rate and standard metabolic rate. An important finding was that contrary to other well-known species, swimming at subcritical speeds in sea bass involves both red and white muscle in different proportions.     

Changes in the dehydrogenase activity of cardiomyocytes during acute experimental arterial occlusion of extremities

The results of quantitative histoenzymologic investigations of succinate dehydrogenase, lactate dehydrogenase and NAD-diaphorase in cardiomyocytes of dogs with acute experimental arterial occlusion in ischemic and postischemic periods are reviewed. An increased activity of dehydrogenases in the early periods (3,6 h) of ischemia and during recirculation was established, with its noticeable reduction at later terms (9,12 h). Medical correction of postischemic disorders was shown to improve cardiomyocyte metabolism.     

The influence of fasting and pancreatectomy on some glycolytic enzymes in the muscle of garden lizard, Calotes versicolor.

The leg muscle of Calotes versicolor consists mainly of white fibers. They can be classified into small, intermediate and broad fibers according to their diameter and staining reaction. The histochemical study of some of the glycolytic enzymes such as aldolase, phosphorylase, lactic dehydrogenase (LDH) and alpha-glycerophosphate dehydrogenase (alpha-GPDH) is described in the muscle of normal, pancreactomized and insulin injected animals. Highest activity of all enzymes was observed in the small fibers, though they occur in negligiable amount (3%). The intermediate and broad fibers exhibited medial and lowest activities respectively. 24 h after the extirpation of the pancreas a considerable inhibition is noted in the activities of phosphorylase, LDH and alpha-GPDH. Induced inanition for 21 days ensued insignificant but gradual decrease and increase in the alpha-GPDH and phosphorylase activities respectively in both unoperated and operated animals. The aldolase shows its mere presence in normal and trace activity in pancreatectomized animals. The injection of insulin (40 i.u./kg) at the interval of 30 min, 60 min, 4 h, 12 h and 24 h is given. The activities of all enzymes is stimulated at 30 min and depleted 4 h after the injection. The level of activity was remaintained at 12 h to 24 h stage. The possible physiological role and significance of enzymes in the synthesis and breakdown of glycogen is discussed.     

Arrhythmic effects of norepinephrine in a model of cardiac ischemia and reperfusion

The aim of this study was to assess the direct effects of norepinephrine on mechanisms of arrhythmia induced by conditions of ischemia followed by reperfusion. Isolated canine Purkinje fiber-papillary muscle preparations were studied using standard microelectrode techniques. Tissues were superfused for 40 min with a solution simulating "ischemia" (i.e., hypoxic, acidotic, elevated lactate, and zero substrate) and then "reperfused" for 60 min. Ischemia produced a moderate loss of membrane potential in both tissues. Reperfusion resulted in rapid polarization of the tissues, which was accompanied by oscillatory afterpotentials and aftercontractions in 6 of 12 and 4 of 12 Purkinje fibers, respectively. This was followed by a progressive loss of membrane potential and inexcitability in Purkinje fibers. Recovery was associated with activity resembling depolarization-induced automaticity in 4 of 12 fibers. Addition of norepinephrine (0.5 microM) to the ischemic and reperfusion solutions altered primarily the reperfusion responses. Oscillatory afterpotentials and aftercontractions were larger and occurred in 8 of 8 and 6 of 8 Purkinje fibers, respectively. Norepinephrine also prevented or blunted the progressive depolarization to inexcitability in Purkinje tissues and increased automaticity occurring at low (depolarization-induced automaticity) and more polarized membrane potentials (enhanced normal pacemaker activity). This study demonstrates that norepinephrine exacerbates several potential mechanisms of arrhythmia elicited by reperfusion in canine Purkinje tissues.     

Functional and morphological changes in the kidneys in acute embologenic arterial occlusion of the extremities

The results of biochemical, radioisotope and morphological investigations of dog kidneys in experimental acute occlusion of hind limb arteries during ischemia and in postischemic periods are reviewed. Morphological and functional changes in the kidneys occur in ischemia. Blood flow recovery in the extremities aggravates these changes leading in 12-hour ischemia to acute renal failure.     

Development of chequerboard pattern in human foetal skeletal muscle.

The study was undertaken to race the histochemical and electron microscopic development patterns of human myogenesis from the 9th to the 26th week of foetal life. Particular attention was paid to the possibility of appearance of metabolic or structural differences between individual skeletal muscle fibres in early periods of myogenesis. The 9th week of foetal life is the period when primitive myotubes are formed. Irregular distribution of the ATPase (pH 9-4) activity observed at this time is due to differences in the structure of fusing myoblasts. The early myotubes show a high activity of the oxidative enzymes and lack of phosphorylase. Conversion of immature muscle cells into structurally mature fibres begins between the 20th and the 24th week. The latter fibres exhibit a uniform activity of all the studied enzymes and thus resemble the intermediate type of fibres of mature muscles. From about the 26th week on the typical mosaic pattern of the enzymatic activity is observed. All the differences in enzymatic activity which appear in fibers prior to their full morphologicaal maturity result from differences in developmental stages of the fibres at the given moment. The present study also suggests that there are no morphological or metabolic differences between individual humanskeletal muscle fibres prior to their metabolic differentiation into types which occurs after their innervation.     

Preservation of skeletal muscle in tissue transfers using rat hindlimbs.

Replantation of major extremities after long periods of ischemia can lead to viable replants in many cases, but functional restoration is often poor owing to fibrosis of the muscle. In this study, maximum hypothermic time in tissue transfers containing skeletal muscle using hindlimbs of Lewis rats preserved in 4 degrees C Euro-Collins solution was investigated. After preserving midthigh amputated legs in this solution for 6, 9, and 12 hours, the legs were transplanted to other inbred rats using microsurgical technique, and 1 week later, gastrocnemii were obtained to analyze ATP, ADP, and AMP using high-performance liquid chromatography. The values were compared with those for healthy legs, nonischemic operated control legs, and legs preserved in the same manner for 6, 9, and 12 hours. Histologic and serologic examinations were conducted. ATP values of the 9-hour preservation group resumed those of the nonischemic operated control group, with the values of the 12-hour preservation group remaining at 61 percent. Histologically, focal necrosis, hyaline degeneration, and regeneration processes were the most characteristic manifestations in the muscles transplanted after cold ischemia of 12 hours. It was concluded that skeletal muscle could be preserved for 9 hours in 4 degrees C Euro-Collins solution.     

CYTOLOGICAL STUDIES OF FIBER TYPES IN SKELETAL MUSCLE : A Comparative Study of the Mammalian Diaphragm

A comparative investigation of the mammalian diaphragm has revealed a correlation between certain cytological aspects of red and white muscle fibers and functional activity. This skeletal muscle presents the advantage of a similar and constant function among the mammals, but its functional activity varies in a quantitative manner. Both the rate of breathing (and hence the rate of contraction of the diaphragm) and metabolic activity are known to be inversely related to body size; and this study has demonstrated a relationship between cytological characteristics of the diaphragm and body size of the animal. Small fibers rich in mitochondria (red fibers) are characteristic of small mammals, which have high metabolic activity and fast breathing rates; and large fibers with relatively low mitochondrial content predominate in large mammals, which have lower metabolic activity and slower breathing rates. In mammals with body size intermediate between these two groups (including the laboratory rat), the diaphragm consists of varying mixtures of fiber types. In general, the mitochondrial content of diaphragm fibers is inversely related to body size. It appears, then, that the red fiber reflects a high degree of metabolic activity or a relatively high rate of contraction within the range exhibited by this muscle.     

Metabolic underpinnings of the paradoxical net phosphocreatine resynthesis in contracting rat gastrocnemius muscle

Net phosphocreatine (PCr) resynthesis during muscle contraction is a paradoxical phenomenon because it occurs under conditions of high energy demand. The metabolic underpinnings of this phenomenon were analyzed non-invasively using 31P-magnetic resonance spectroscopy in rat gastrocnemius muscle (n=11) electrically stimulated (7.6 Hz, 6 min duration) in situ under ischemic and normoxic conditions. During ischemic stimulation, [PCr] initially fell to a steady state (9+/-5% of resting concentration) which was maintained for the last 5 min of stimulation, whereas isometric force production decreased to a non-measurable level beyond 3 min. Throughout normoxic stimulation, [PCr] and force production declined to a steady state after respectively 1 min (5+/-3% of resting concentration) and 3.25 min (21+/-8% of initial value) of stimulation. Contrary to the observations under ischemia, a paradoxical net PCr resynthesis was recorded during the last 2 min of normoxic stimulation and was not accompanied by any improvement in force production. These results demonstrate that the paradoxical net PCr resynthesis recorded in contracting muscle relies exclusively on oxidative energy production and could occur in inactivated fibers, similarly to PCr resynthesis during post-exercise recovery.