Posthatching changes in levels and molecular forms of acetylcholinesterase in slow and fast muscles of the chicken: Effects of denervation and direct electrical stimulation

The evolution of acetylcholinesterase (AChE) activity and AChE molecular form distribution were studied in slow-tonic anterior latissimus dorsi (ALD) and in fast-twitch posterior latissimus dorsi (PLD) muscles of chickens 2-18 days of age. In ALD as well as in PLD muscles, the AChE-specific activity increased transiently from day 2 to day 4; the activity then decreased more rapidly in PLD muscle. During this period asymmetric AChE forms decreased dramatically in ALD muscle and the globular forms increased. In PLD muscle, the most striking change was the decline in A8 form between days 2 and 18 of development. Denervation performed at day 2 delayed the normal decrease in AChE-specific activity in PLD muscle, whereas little change was observed in ALD muscle. Moreover, A forms in these two muscles were virtually absent 8 days after denervation. Direct electrical stimulation depressed the rise in AChE-specific activity in denervated PLD muscle and prevented the loss of the A forms. Furthermore, the different molecular forms varied according to the stimulus pattern. In ALD muscle, electrical stimulation failed to prevent the effect of denervation. This study emphasizes the differential response of denervated slow and fast muscles to electrical stimulation and stresses the importance of the frequency of stimulation in the regulation of AChE molecular forms in PLD muscle during development.     

Induction of oxidatively modified proteins in skeletal muscle by electrical stimulation and its suppression by dietary supplementation of (-)-epigallocatechin gallate

The oxidative stress produced by electrical stimulation-induced muscle contraction was examined in the skeletal muscle proteins of rats that had been fed on the dietary flavonoid, (-)-epigallocatechin gallate (EGCg). Electrical stimulation of the rat leg muscle every second day for a two-week period resulted in an increased (p < 0.05) muscle weight and accumulation of oxidatively induced modified proteins. Similar stimulation conducted every day for only one week had no effect on the muscle weight or protein oxidation, although the rate of protein degradation increased. Rats fed on a 20% casein diet supplemented with 0.1% EGCg for 2 weeks responded to the electrical stimulation of muscle contraction by reducing the increased muscle protein carbonyl content when compared to their counterparts fed on a control diet. There was no change in activity of antioxidative enzymes in muscle tissue of the EGCg-fed rats receiving electrical stimulation. The results of this study show that the antioxidative property of EGCg was effective for suppressing oxidative modification of the skeletal muscle protein induced by electrical stimulation. This finding demonstrates that EGCg has a beneficial effect in vivo on the free radical-mediated oxidative damage to muscle proteins.     

Effects of Electrical Stimulation on Molecular Forms of Butyrylcholinesterase in Denervated Fast and Slow Latissimus Dorsi Muscles of Newly Hatched Chicken

The effects of denervation and direct electrical stimulation upon the activity and the molecular form distribution of butyrylcholinesterase (BuChE) were studied in fast-twitch posterior latissimus dorsi (PLD) and in slow-tonic anterior latissimus dorsi (ALD) muscles of newly hatched chicken. In PLD muscle, denervation performed at day 2 substantially reduced the rate of rapid decrease of BuChE specific activity which takes place during normal development, whereas in the case of ALD muscle little change was observed. Moreover, the asymmetric forms which were dramatically reduced in denervated PLD muscle were virtually absent in denervated ALD muscle at day 14. Denervated PLD and ALD muscles were stimulated from day 4 to day 14 of age. Two patterns of stimulation were applied, either 5-Hz frequency (slow rhythm) or 40-Hz frequency (fast rhythm). Both patterns of stimulation provided the same number of impulses per day (about 61,000). In PLD muscle, electrical stimulation almost totally prevented the postdenervation loss in asymmetric forms and led to a decrease in BuChE specific activity. In ALD muscle, electrical stimulation partially prevented the asymmetric form loss which occurs after denervation. This study emphasizes the role of evoked muscle activity in the regulation of BuChE asymmetric forms in the fast PLD muscle and the differential response of denervated slow and fast muscles to electrical stimulation.     

Induction of Oxidatively Modified Proteins in Skeletal Muscle by Electrical Stimulation and Its Suppression by Dietary Supplementation of (-)-Epigallocatechin Gallate

The oxidative stress produced by electrical stimulation-induced muscle contraction was examined in the skeletal muscle proteins of rats that had been fed on the dietary flavonoid, (-)-epigallocatechin gallate (EGCg). Electrical stimulation of the rat leg muscle every second day for a two-week period resulted in an increased (p<0.05) muscle weight and accumulation of oxidatively induced modified proteins. Similar stimulation conducted every day for only one week had no effect on the muscle weight or protein oxidation, although the rate of protein degradation increased. Rats fed on a 20% casein diet supplemented with 0.1% EGCg for 2 weeks responded to the electrical stimulation of muscle contraction by reducing the increased muscle protein carbonyl content when compared to their counterparts fed on a control diet. There was no change in activity of antioxidative enzymes in muscle tissue of the EGCg-fed rats receiving electrical stimulation. The results of this study show that the antioxidative property of EGCg was effective for suppressing oxidative modification of the skeletal muscle protein induced by electrical stimulation. This finding demonstrates that EGCg has a beneficial effect in vivo on the free radical-mediated oxidative damage to muscle proteins.     

beta-Glucuronidase activity in trained red and white skeletal muscle of mice.

We studied the effects of prolonged running exercise (5 days a week, 1.5 h per day at a speed of 17.6 m/min) on the activity of some acid hydrolases (beta-glucuronidase, beta-N-acetylglucosaminidase, acid phosphatase and cathepsin D) and three enzymes of energy metabolism (cytochrome c oxidase, lactate dehydrogenase and creatine kinase) in the distal and in the proximal, the predominantly white and red parts, respectively, of the vastus lateralis-muscle from mice. The acid hydrolase activity levels were 1.24--1.69 higher in untrained red muscle compared to untrained white muscle. The light training applied increased the activity of beta-glucuronidase in both red and white muscle. No other significant training effects were observed in the enzyme activities measured.     

Effect of electrical stimulation post mortem of bovine muscle on the binding of glycolytic enzymes. Functional and structural implications.

The extent of binding of glycolytic enzymes to the particulate fraction of homogenates was measured in bovine psoas muscle before and after electrical stimulation. In association with an accelerated glycolytic rate on stimulation, there was a significant increase in the binding of certain glycolytic enzymes, the most notable of which were phosphofructokinase, aldolase, glyceraldehyde 3-phosphate dehydrogenase and pyruvate kinase. From the known association of glycolytic enzymes with the I-band of muscle it is proposed that electrical stimulation of anaerobic muscle increases enzyme binding to actin filaments. Calculations of the extent of enzyme binding suggest that significant amounts of enzyme protein, particularly aldolase and glyceraldehyde 3-phosphate dehydrogenase, are associated with the actin filaments. The results also imply that kinetic parameters derived from considerations of the enzyme activity in the soluble state may not have direct application to the situation in the muscle fibre, particularly during accelerated glycolysis.     

Effects of denervation and direct electrical stimulation upon acetylcholine receptors and acetylcholinesterase accumulation in developing latissimus dorsi muscle of the chick

The effects of denervation and of direct electrical stimulation of denervated muscle upon the acetylcholine receptor (AChR) clusters and acetylcholinesterase (AChE) spots in the fast avian muscle posterior latissimus dorsi have been investigated. Denervation at day 2 after hatching leads to a disappearance of the junctional AChR clusters and to a marked decrease of AChE spots. Direct electrical stimulation of denervated muscle allows the maintenance of AChR clusters and partly prevents the loss of AChE spots. When AChR cluster and post-synaptic AChE have disappeared in a denervated muscle, muscle activity induced by direct stimulation is unable to induce their accumulation.     

Possible correlation between binding of muscle type AMP deaminase to myofibrils and ammoniagenesis in rat skeletal muscle on electrical stimulation

Contraction of rat skeletal muscle by electrical stimulation of the sciatic nerve caused remarkable increase in binding of AMP deaminase (EC 3.5.4.6) to myofibrils, but did not change the total enzyme activity. After 30 sec stimulation, the ratio of bound to free enzyme was about 5 times that in resting muscle. This treatment also increased the ammonia content of the muscle to 5 times that in resting state. From these findings, we suggest that there is a correlation between the binding of muscle type AMP deaminase to myofibrils and ammoniagenesis in the muscle.     

Optimal stimulation of paralyzed muscle after human spinal cord injury.

Muscle properties change profoundly as a result of disuse after spinal cord injury. To study the extent to which these changes can be reversed by electrical stimulation, tibialis anterior muscles in complete spinal cord-injured subjects were stimulated for progressively longer times (15 min, 45 min, 2 h, and 8 h/day) in 6-wk intervals. An index of muscle endurance to repetitive stimulation doubled (from 0.4 to 0.8), contraction and half-relaxation times increased markedly (from 70 to approximately 100 ms), but little or no change was measured in twitch or tetanic tension with increasing amounts of stimulation. The changes observed with 2 h/day of stimulation brought the physiological values close to those for normal (control) subjects. A decrease in the stimulation period produced a reversal of the changes. No effects were observed in the contralateral (unstimulated) muscle at any time, nor was there evidence of decreased numbers of motor units in these subjects secondary to spinal cord injury. Motor unit properties changed in parallel with those of the whole muscle. The occasional spasms occurring in these subjects are not sufficient to maintain normal muscle properties, but these properties can largely be restored by 1-2 h/day of electrical stimulation.     

The effects of low frequency electrical stimulation on satellite cell activity in rat skeletal muscle during hindlimb suspension

Background  

The ability of skeletal muscle to grow and regenerate is dependent on resident stem cells called satellite cells. It has been shown that chronic hindlimb unloading downregulates the satellite cell activity. This study investigated the role of low-frequency electrical stimulation on satellite cell activity during a 28 d hindlimb suspension in rats.     

Comparison of premodulated interferential and pulsed current electrical stimulation in prevention of deep muscle atrophy in rats

The goal of this study was to compare the effects of electrical stimulation using pulsed current (PC) and premodulated interferential current (IC) on prevention of muscle atrophy in the deep muscle layer of the calf. Rats were randomly divided into 3 treatment groups: control, hindlimb unloading for 2 weeks (HU), and HU plus electrical stimulation for 2 weeks. The animals in the electrical stimulation group received therapeutic stimulation of the left (PC) or right (IC) calf muscles twice a day during the unloading period. Animals undergoing HU for 2 weeks exhibited significant loss of muscle mass, decreased cross-sectional area (CSA) of muscle fibers, and increased expression of ubiquitinated proteins in the gastrocnemius and soleus muscles compared with control animals. Stimulation with PC attenuated the effects on the muscle mass, fiber CSA, and ubiquitinated proteins in the gastrocnemius muscle. However, PC stimulation failed to prevent atrophy of the deep layer of the gastrocnemius muscle and the soleus muscle. In contrast, stimulation with IC inhibited atrophy of both the gastrocnemius and soleus muscles. In addition, the IC protocol inhibited the HU-induced increase in ubiquitinated protein expression in both gastrocnemius and soleus muscles. These results suggest that electrical stimulation with IC is more effective than PC in preventing muscle atrophy in the deep layer of limb muscles.     

Coordination between the electrical activity of developing indirect flight muscles and the firing activity of a population of neurosecretory cells in the silkmoth, Bombyx mori

The developing indirect flight muscles of pharate moths are characterized by a rhythmic discharge of a long bout of flight-pattern-like muscle potentials in the absence of contractions. The electrical activity of the dorsal longitudinal flight muscles (DLMs) in the silkmoth, Bombyx mori, was discernible as a cluster of many series of muscle potentials that last for several minutes on day 4 of the pupal period. The duration of the active phases and the period of rhythmic activity gradually increased to a peak value on day 7 or 8 and then declined until the end of the pupal period. Mean duration of the active phases (+/-SD) and the mean period of the rhythmic activity (+/-SD) at the peak were 38.7+/-8.7 min and 74.5+/-7.3 min, respectively. The rhythmic electrical activity of immature DLMs was closely coordinated with the rhythmic (bursting) activity of a population of neurosecretory cells that are known to produce pheromone-biosynthesis activating neuropeptide (PBAN) and its related peptides, which belong to the multifunctional peptide family, pyrokinin/PBAN. The DLMs always became active a few minutes after the neurosecretory cells, and the timing of onset of these two activities appeared to be strictly regulated by a neural mechanism. The implication of the coordinated activity for development and maturation of imaginal tissues, including the flight motor system, and possible functions of the neuropeptides in this development are discussed.     

Activation of malonyl-CoA decarboxylase in rat skeletal muscle by contraction and the AMP-activated protein kinase activator 5-aminoimidazole-4-carboxamide-1-beta -D-ribofuranoside

Alterations in the concentration of malonyl-CoA, an inhibitor of carnitine palmitoyltransferase I, have been linked to the regulation of fatty acid oxidation in skeletal muscle. During contraction decreases in muscle malonyl-CoA concentration have been related to activation of AMP-activated protein kinase (AMPK), which phosphorylates and inhibits acetyl-CoA carboxylase (ACC), the rate-limiting enzyme in malonyl-CoA formation. We report here that the activity of malonyl-CoA decarboxylase (MCD) is increased in contracting muscle. Using either immunopurified enzyme or enzyme partially purified by (NH(4))(2)SO(4) precipitation, 2-3-fold increases in the V(max) of MCD and a 40% decrease in its K(m) for malonyl-CoA (190 versus 119 micrometer) were observed in rat gastrocnemius muscle after 5 min of contraction, induced by electrical stimulation of the sciatic nerve. The increase in MCD activity was markedly diminished when immunopurified enzyme was treated with protein phosphatase 2A or when phosphatase inhibitors were omitted from the homogenizing solution and assay mixture. Incubation of extensor digitorum longus muscle for 1 h with 2 mm 5-aminoimidazole-4-carboxamide-1-beta-d-ribofuranoside, a cell-permeable activator of AMPK, increased MCD activity 2-fold. Here, too, addition of protein phosphatase 2A to the immunopellets reversed the increase of MCD activity. The results strongly suggest that activation of AMPK during muscle contraction leads to phosphorylation of MCD and an increase in its activity. They also suggest a dual control of malonyl-CoA concentration by ACC and MCD, via AMPK, during exercise.     

Preferential ipsilateral influence of the posterior hypothalamus on the neocortex

On the 10th–20th day after precollicular transection of the brain stem weak low-frequency electrical stimulation of the posterior hypothalamus preferentially activates the ipsilateral neocortex. After unilateral injury to the posterior hypothalamus, synchronous activity predominates in the ipsilateral neocortex. In premesencephalic animals weak single electrical stimulation of the posterior hypothalamus evokes the appearance of spindles in ipsilateral zones of the frontal cortex, whereas stronger single stimulation causes the diffuse generation of spindles in various parts of the neocortex. Besides this preferential unilateral effect, the influence of the posterior hypothalamus is found to be more strongly expressed in the frontal than in the occipital cortex. It is postulated that the posterior hypothalamus exerts its influence on the neocortex through the thalamic nuclei.Institute of Physiology, Academy of Sciences of the Georgian SSR, Tbilisi. Translated from Neirofiziologiya, Vol. 8, No. 2, pp. 139–145, March–April, 1976.     

Skeletal muscle and heart LKB1 deficiency causes decreased voluntary running and reduced muscle mitochondrial marker enzyme expression in mice

LKB1 has been identified as a component of the major upstream kinase of AMP-activated protein kinase (AMPK) in skeletal muscle. To investigate the roles of LKB1 in skeletal muscle, we used muscle-specific LKB1 knockout (MLKB1KO) mice that exhibit low expression of LKB1 in heart and skeletal muscle, but not in other tissues. The importance of LKB1 in muscle physiology was demonstrated by the observation that electrical stimulation of the muscle in situ increased AMPK phosphorylation and activity in the wild-type (WT) but not in the muscle-specific LKB1KO mice. Likewise, phosphorylation of acetyl-CoA carboxylase (ACC) was markedly attenuated in the KO mice. The LKB1KO mice had difficulty running on the treadmill and exhibited marked reduction in distance run in voluntary running wheels over a 3-wk period (5.9 +/- 0.9 km/day for WT vs. 1.7 +/- 0.7 km/day for MLKB1KO mice). The MLKB1KO mice anesthetized at rest exhibited significantly decreased phospho-AMPK and phospho-ACC compared with WT mice. KO mice exhibited lower levels of mitochondrial protein expression in the red and white regions of the quadriceps. These observations, along with previous observations from other laboratories, clearly demonstrate that LKB1 is the major upstream kinase in skeletal muscle and that it is essential for maintaining mitochondrial marker proteins in skeletal muscle. These data provide evidence for a critical role of LKB1 in muscle physiology, one of which is maintaining basal levels of mitochondrial oxidative enzymes. Capacity for voluntary running is compromised with muscle and heart LKB1 deficiency.     

Transformation of the afferent tactile signal into a motor command in the cat motor cortex

Activity of 112 neurons of the precruciate motor cortex in cats was studied during a forelimb placing reaction to tactile stimulation of its distal parts. The latent period of response of the limb to tactile stimulation was: for flexors of the elbow (biceps brachii) 30–40 msec, for the earliest reponses of cortical motor neurons about 20 msec. The biceps response was observed 5–10 msec after the end of stimulation of the cortex with a series of pulses lasting 25 msec. Two types of excitatory responses of the neurons were identified: responses of sensory type observed to each tactile stimulation of the limb and independent of the presence or absence of motion, and responses of motor type, which developed parallel with the motor response of the limb and were not observed in the absence of motion. The minimal latent period of the responses of motor type was equal to the latent period of the sensory responses to tactile stimulation (20±10 msec). Stimulation of the cortex through the recording microelectrode at the site of derivation of unit activity, which increased during active flexion of the forelimb at the elbow (11 stimuli at intervals of 2.5 msec, current not exceeding 25 µA), in 70% of cases evoked an electrical response in the flexor muscle of the elbow.M. V. Lomonosov Moscow State University. Translated from Neirofiziologiya, Vol. 9, No. 2, pp. 115–123, March–April, 1977.     

Oxidative capacity of tissues contributing to thermogenesis in eider (Somateria mollissima) ducklings: changes associated with hatching

1. The development of liver and skeletal muscle oxidative capacities during hatching of the common eider (Somateria mollissima) in the Arctic has been investigated by monitoring tissue cytochrome c oxidase activity. 2. The specific activity of the liver enzyme did not change as the embryo underwent hatching, nor during subsequent growth of the duckling into adulthood. 3. Thigh muscle enzyme specific activity increased by a factor of 3.4 during the 24 h prehatching period, remained elevated for at least 48 h after hatching, and then returned to the embryonic (-24 h) level in adults. 4. Histochemically visualized NADH-tetrazolium reductase of a typical red thigh muscle, M. vastus lateralis, showed a distinct increase in activity as the hatching process progressed to completion. 5. Electron microscopy of sectioned M. vastus lateralis revealed a dramatic increase in the density of the myofibrillar structure (number of mitochondrial profiles per unit area), and in the surface area of mitochondrial crista membranes in the course of the 48 h interval from 1 day prehatching to 1 day after hatching. 6. The significance of these changes for the scaling of thermoregulatory heat generation in the newly hatched eider duckling is discussed.     

Histochemical fibre types in the lateral muscle of fishes in fresh, brackish and salt water

The histochemical pattern of red, pink and white muscle of fish living in fresh, brackish, and salt water is reported. The muscle fibres were stained routinely during the year for lactate dehydrogenase (LDH), menadione α-glycerophosphate dehydrogenase (Mα—GPDH), succinic dehydrogenase (SDH), myosin adenosine triphosphatase (myosin ATPase), phosphorylase, lipids and glycogen. The pink and red muscles contain more glycogen and lipids and have a higher SDH activity, which is in accord with their aerobic metabolism and function in sustained swimming activity. The acid labile myosin ATPase activity characteristic of fast twitch fibres is present in the white fibres of most species, however in the white muscle of Gobius paganellus the enzyme activity is stable to both acid and alkali and, in addition, there is a scattered distribution of different fibre types in red and, especially, pink muscle. A study of seasonal variation patterns of myosin ATPase in white muscle of mugilidae over a period of two years has demonstrated, in late summer, the appearance of new small diameter fibres, with a high acid stable enzyme activity, that develop into the large diameter acid labile fibres.     

The development of alkaline phosphatase in trichinous muscle.

The development of alkaline phosphatase during invasion and encystment of Trichinella spiralis in rat skeletal muscle fibres was studied at the ultrastructural level. On day 14 after infection, the enzymatic activity is found in proliferating parts of the T-tubular system and in parts of the plasmalemma. In cells, in which a strong hyperplasia of this system is noted. AlPase is present in the abundant network of stratified and concentric membranes from which a large number of pinocytic vesicles arise. From day 50 till 1 year after infection the enzyme activity was invariably present in the matrix surrounding the larvae and was confined to the enormous amounts of cytoplasmic membranes. The possible functional significance of this enzyme in the matrix, in view of its peculiar localization in the immediate vicinity of the parasite, is discussed. In the presence of 0.1 mM of the levamisole analogue, compound R 30402, which is a stereospecific inhibitor of AlPase, the activity is completely lost.