Fast-contracting Muscle Research Articles

The qualification of different free muscle transplants to reconstruct mimic function: an experimental study in rabbits.

With the scutuloauricularis muscle, we developed a new model for experimental free transplantation of mimic muscles in the rabbit and studied the qualification of different muscles for free functional grafting into the position of the facial muscle, which is to be replaced. Forty adult female white New Zealand rabbits were distributed to four groups of 10 rabbits each. In group 1, the operative techniques of the new transplantation models were developed in the scutuloauricularis muscle, the pectoralis descendens muscle, and a comparable part of the rectus femoris muscle. In group 2, the scutuloauricularis muscle was transplanted orthotopically with microneurovascular anastomoses on the left side; in group 3, the pectoralis descendens muscle was transplanted into the position of the scutuloauricularis after its removal; and with the animals in group 4, a piece of the rectus femoris muscle was transplanted into the position of the mimic muscle after its removal. In all muscle transplants, the neurovascular supply was reestablished microsurgically by end-to-end anastomoses to the superficial temporal vessels and direct nerve coaptation to the facial nerve branches supplying originally the scutuloauricularis muscle. Nine months after transplantation, force measurements were performed in all transplanted muscles and the scutuloauricularis muscles of the control side. Cross-sections stained for ATPase after alkaline preincubation at pH 10.4 were used for computer-assisted planimetry of the muscle fibers. The orthotopically transplanted scutuloauricularis muscles reached with 2.84 (+/-1.04) N for maximal tetanic tension on the average 87.7 (+/-32.1) percent of that of the control scutuloauricularis muscles, the pectoralis descendens muscles with 4.25 (+/-2.15) N on the average 188.7 (+/-100.7) percent of that of the controls, and the pieces of rectus femoris muscles 6.62 (+/-2.16) N or 185.3 (+/-45.4) percent of that of the controls. All three muscles were identified as fast contracting muscles before and after transplantation. By transplantation, the content of type II muscle fibers changed from 58.2 to 68.0 percent in the scutuloauricularis muscle, from 62.4 to 74.4 percent in the musculus pectoralis descendens, and from 92.5 to 82.8 percent in the rectus femoris muscle. For the first time, an experimental model for free transplantation of mimic muscles was developed and functionally assessed. The most important result of this study was the fact that the double-sized muscle grafts developed twice the force of the control scutuloauricularis muscles, although reinnervated by the original muscle nerve branch. This result underlines the usefulness of overdimensioning during clinical muscle transplantation. It was also shown that parts of big muscles can be grafted with results similar to those experienced with complete smaller muscles.

Role of Parvalbumin in Skeletal Muscle Relaxation

Parvalbumin, a soluble intracellular calcium buffer, is present in high concentrations in fast-contracting skeletal muscles across the animal kingdom. In frog skeletal muscle, pharmacological or low-temperature inhibition of the sarcoplasmic reticulum calcium pump reveals that parvalbumin sequesters calcium and promotes relaxation at a rate determined by magnesium dissociation from parvalbumin.

Selection for rapid growth increases the number and the size of muscle fibres without changing their typing in chickens.

Quantitative (muscle fibre number and cross-sectional areas) and qualitative (myosin isoforms and metabolic enzyme activities) characteristics of two muscles, M. pectoralis major and M. anterior latissimus dorsi, were compared among male chickens of two lines during growth from hatching to adulthood. The lines were derived from a divergent selection based on growth rate. The two muscles were chosen on the basis of their histochemical profile. Pectoralis major muscle contains only fast contracting muscle fibres whereas anterior latissimus dorsi muscle is almost entirely made up with slow contracting fibres. At both ages, the two lines showed similar fibre type distributions. At hatching, fibre cross-sectional areas were equivalent in the two lines, but after the first week, animals from the fast growing line exhibited wider fibre areas, whatever the muscle, than animals from the slow growing line. The total number of fibres in a muscle was found greater in the fast growing line, irrespective of whether it was exactly determined (anterior latissimus dorsi muscle, + 20%) or only estimated (pectoralis major muscle). This number remains constant in the two lines throughout the growth. Myosin isoform profiles and metabolic enzyme activities were similar in the two lines, at both ages, and were in good agreement with the histochemical muscle fibre profiles.

Quantification of the soluble calcium-binding protein (SCBP) in various muscle tissues of the terrestrial oligochaete Lumbricus terrestris L.

The soluble calcium-binding protein (SCBP) from the body wall muscle of Lumbricus terrestris can be assumed to be the counterpart of the high-affinity calcium-binding protein parvalbumin (PV) from vertebrate muscle, the physiological role of which remains to be established. It is proposed that these proteins could act as soluble relaxing factors, especially in fast contracting muscles (Gerday, 1988). One of the experimental findings supporting this idea is the correlation between the relaxation speed of a muscle and its content of PV. We have been prompted to perform a quantitative analysis on various types of muscle of the terrestrial oligochaete L. terrestris in order to verify the above mentioned correlation for the case of an invertebrate species. The results presented in this report indicate that the amount of SCBP within the body wall muscle is three orders of magnitude higher as compared to the gizzard muscle of L. terrestris.

Histomorphometric Studies in Patients with Facial Palsy Treated by Functional Muscle Transplantation: New Aspects for the Surgical Concept

Whenever it was possible, muscle and nerve biopsies were performed in patients with irreversible, unilateral facial palsy treated by cross-face nerve grafting and free gracilis muscle transplantation with microneurovascular anastomoses. Planimetric analyses of cross-sections showed the following, to some extent, surprising, results: (1) Independent of the final functional result, approximately the same number of regenerated, thin nerve fibers (100-200) were found in the distal end of the cross-face nerve graft at the time of muscle transplantation. These are approximately 20% of the nerve fibers counted in the branches of the facial nerve at the healthy side used for reinnervation. (2) There is no correlation between the number or diameter of the nerve fibers in the distal end of the cross-face nerve graft and the functional recovery of the transplanted muscle, but there is good correlation between the morphology of the fibers of the muscle graft and the functional result. (3) Different portions of slow-contracting and fast-contracting muscle fibers in the reinnervated muscle grafts showed the strong influence of the quality of the nerve used for the crossover innervation. If a facial nerve branch innervating the slow buccinator muscle was used, the originally fast gracilis muscle was transformed to a slow muscle by this kind of reinnervation. These important findings are the basis of a new view of surgery in the treatment of irreversible facial palsy by functional free-muscle transplantation.

Slow and fast contracting rat skeletal muscles differ in plasminogen activator activities

Slow and fast contracting rat skeletal muscles differ in plasminogen activator activities

Identification and characterization of a tissue kallikrein in rat skeletal muscles.

A tissue kallikrein was purified from rat skeletal muscle. Characterization of the enzyme showed that it has alpha-N-tosyl-L-arginine methylesterase activity and releases kinin from purified bovine low-Mr kininogen substrate. The pH optimum (9.0) of its esterase activity and the profile of inhibition by serine-proteinase inhibitors are identical with those of purified RUK (rat urinary kallikrein). Skeletal-muscle kallikrein also behaved identically with urinary kallikrein in a radioimmunoassay using a polyclonal anti-RUK antiserum. On Western-blot analysis, rat muscle kallikrein was recognized by affinity-purified monoclonal anti-kallikrein antibody at a position similar to that of RUK (Mr 38,000). Immunoreactive-kallikrein levels were measured in skeletal muscles which have different fibre types. The soleus, a slow-contracting muscle with high mitochondrial oxidative-enzyme activity, had higher kallikrein content than did the extensor digitorum longus or gastrocnemius, both fast-contracting muscles with low oxidative-enzyme activity. Streptozotocin-induced diabetes reduced muscle weights, but did not alter the level of kallikrein (pg/mg of protein) in skeletal muscle, suggesting that insulin is not a regulator of kallikrein in this tissue. Although the role of kallikrein in skeletal muscle is unknown, its localization and activity in relation to muscle functions and disease can now be studied.

Physico-chemical properties of rat and dog cardiac α-actinin

α-Actinin exists in several polymorphic forms which appear to be characteristic of the muscle type from which it is isolated. In order to determine the possible physiological role of this structural protein in cardiac muscle, we describe and compare here the physico-chemical properties of cardiac α-actinin from two different mammalian species, rat (fast contracting muscle) and dog (slow contracting muscle). Purification of cardiac α-actinin was achieved by chromatography on DEAE-cellulose and hydroxyapatite columns. The α-actinins isolated were different in their electrophoretic mobility (SDS-polyacrylamide gel electrophoresis), molecular size and α-helical content. However, their shape as revealed by electron microscopy and their activating effect on Mg 2+-ATPase activity of actomyosin appear to be similar. These studies suggest that the rat and dog cardiac α-actinin are structurally different but functionally similar proteins.

Effect of stretch combined with electrical stimulation on the type of sarcomeres produced at the ends of muscle fibers

Stretching a muscle results in a rapid addition of sarcomeres at the ends of the muscle fibers. The effect of a pattern of electrical stimulation resembling that of a slow motoneuron on the newly formed muscle tissue in a stretched, fast-contracting muscle was investigated. We found that after a period as short as 4 days, the type of sarcomeres which were added on to the ends of the existing myofibrils differed from those in the middle regions of the experimental muscles: there was a much higher proportion of type I and type IIA sarcomeres in the stretch-stimulated ends. This study showed that reprogramming of the synthesis of fiber type-specific contractile proteins can be achieved and detected within a very short time by using electrical stimulation combined with stretch.

Enzyme activities of purine catabolism and salvage in human muscle tissue.

Metabolic differentiation in muscle is closely related to the elementary systems of energy supplying metabolism. Most strikingly this is reflected at the level of enzymatic organization (1). White (fast) muscle is characterized by high capacities of glyco-genolysis, glycolysis and lactate fermentation, whereas the capacities of glucose phosphorylation, citric acid cycle, oxidative phosphorylation and fatty acid oxidation are low. Red (slow) muscles, heart and smooth muscles show inverse characteristics. Alterations of enzyme activities during red and white muscle differentiation in vitro suggest the existence of one myogenic cell with the potential to exhibit those properties which are characteristic for any type of muscle (2). According to this concept the dichotomy between white and red muscles becomes apparent after innervation. Furthermore it was demonstrated that white (fast contracting) muscles can be transformed into red (slow contracting) muscles by longterm electric stimulation with low frequencences (3, 4). The adaptation to the nerval stimulus was reflected by structural changes and by alterations in the activites of enzymes (4).

Factors determining the variation of the afterhyperpolarization duration in cat lumbar α-motoneurons

The duration of the afterhyperpolarization (AHP) in cat spinal α-motoneurons varies systematically with motoneurone type, being shorter in motoneurones projecting to fast-contracting muscle units. Recent experiments have shown that the AHP duration is correlated with the amount of sag found in the voltage response to injected constant current pulses. Using a model of the sag process, the present study shows that this correlated is likely to be causal to a substantial extent. Short AHP durations in fast motoneurones may thus be as much, or more, a consequence of a more developed sag process than of faster kinetics of the K conductance process underlying the AHP. This notion is also supported by the experimental observation of a decreased amount of sag and a prolonged AHP duration after axotomy.

Denervation of newborn rat muscle does not block the appearance of adult fast myosin heavy chain.

Several observations, both in vivo and in vitro, have indicated that the development and maturation of mammalian skeletal muscle fibres is influenced by nerve-muscle interactions. Morphological maturation of newly regenerated adult mouse muscle fibers in an organotypic nerve-muscle culture system depends on the presence of spinal cord neurones. Sciatic nerve transection in newborn rats has been shown to modify the development of the histochemical and contractile properties of the denervated muscles. In addition, neural influences are important for the appearance of certain of the myosin small subunits. It has been proposed that the nerve also controls the changes in myosin heavy chain isozymes appearing during development. One such transition occurs in rat muscle where the neonatal form of myosin heavy chain is replaced by the adult form during the second post-natal week. Here we demonstrate that innervation of the rat gastrocnemius muscle (a fast-contracting muscle in the adult) is not required for the appearance of the adult form of myosin heavy chain.

Calcium-binding protein parvalbumin is associated with fast contracting muscle fibres.

The basic mechanism underlying the contraction–relaxation cycle of vertebrate muscles is a Ca2+ exchange between the sarcoplasmic reticulum and the myofibrils. Relaxation is achieved by retrieval of Ca2+ from the myofibrils and transfer to the sarcoplasmic reticulum. However, it is uncertain whether the rate of Ca2+ uptake by the sarcoplasmic reticulum can account for the known speed of relaxation1,2. In fast contracting muscles the Ca2+-binding protein parvalbumin is postulated to facilitate relaxation3–8. Using immunohistochemical techniques, we show here that parvalbumin is located exclusively in type II (fast-twitch) mammalian skeletal muscle fibres which can be further subdivided into five subgroups displaying distinct staining intensities. As the active state decays more rapidly in fast than in slow muscles9,10, our results support the contention that parvalbumin may be concerned with rapid muscle relaxation3–8 and in addition suggest a range of relaxation properties in muscle fibres belonging to the same histochemical fibre type.

Mechanical properties of tenotomized and denervated-tenotomized muscles

Mechanical properties of rat soleus and plantaris muscles were studied in vitro following tenotomy, denervation, or tenotomy plus denervation, all of 3 wk duration. Controls included muscles from sham-operated animals and from animals with muscle tendons severed but immediately resutured. Results of twitch times, times to peak tension, and times to half-relaxation for 145 muscles clearly showed that the slight increase in muscle speed that occurs in the soleus muscles only is due to severance of the muscle tendon per se and not related to muscle shortening and possible related alterations in muscle spindle activity that occurs in simple tenotomy. Furthermore, any demonstrable mechanical changes that occur with tenotomy or with section and resuturing of the tendon requires the presence of intact innervation. We conclude that, contrary to published opinion, tenotomy does not transform slow contracting muscles into fast contracting muscles and that comments concerning the role of stretch receptors in this postulated transformation are pure conjecture, unsupported by experimental data.

Comparative actions of substances affecting cyclic AMP metabolism on the isometric contractions of fast and slow skeletal muscle during single-pulse and subtetanic stimulation

Increasing concentrations of isoprenaline (0.5–4 μM) produced a dose-dependent increase in both T D and dT/dt max during direct single-pulse stimulation of hemidiaphragm of the rat. The same drug during the same type of stimulation produced an insignificant change in these parameters of the isometric contraction of the isolated guinea-pig soleus muscle. On the contrary, isoprenaline produced a dose-dependent decrease of the isometric contraction during subtetanic stimulation of the soleus muscle. Contrary to the results obtained on hemidiaphragm, there was no interaction between halothane and aminophylline on the soleus muscle. In the soleus muscle, aminophylline (0.3–3.2 mM) produced a dose-dependent increase in T D and dT/dt max during single-pulse stimulation, whereas isoprenaline failed to do so under the same experimental conditions, in spite of the fact that both substances are activators of cyclic AMP system. The β 2-selective adrenoceptor agonist terbutaline acted in the same way as isoprenaline. During subtetanic stimulation aminophylline (0.3–3.2 mM) produced a dose-dependent decrease of both parameters of the isometric contraction of hemidiaphragm, which is opposite to the results obtained during single-pulse stimulation. It is concluded that various types of electrical stimulation can produce different responses in slow and fast-contracting muscles, depending on the fundamental biochemical differences of two types of muscle, but some of these responses are the same irrespective of the method of muscle activation.

Calcium transients in mammalian muscles.

Contraction of vertebrate skeletal muscle is caused by calcium ions released from the sarcoplasmic reticulum (see refs 1, 2 for reviews). The ensuing transient change in the intracellular level of ionised calcium has been monitored using various Ca2+ indicators, sich as murexide, aequorin, and arsenazo III. So far, most of what is known about these calcium transient derives from experiments on barnacle or frog muscles fibres, and it is desirable to extend such studies to mammalian muscle. We report here that the photoprotein aequorin can be used to monitor calcium transients in rat and human muscles, and that the transients decay more quickly in fast contracting muscle fibres.

On the possible role of potassium ions in the action of terbutaline on skeletal muscle contractions.

The soleus, a slow-contracting, and the extensor digitorum longus (EDL), a fast-contracting muscle from guinea-pig were prepared for isometric recording in vitro, and the effect of terbutaline, a beta-adrenoceptor agonist, was studied during various experimental conditions. In the soleus terbutaline caused an initial depression of the force of contraction followed by an increase. The degree of fusion of subtetanic contractions was reduced throughout the experiment. The EDL responded with an increased force only. The force of contraction of the two muscles increased with the K+-ion concentration of the medium up to 6 mM. Higher concentrations of K+ caused a depression which was partly prevented by terbutaline. When the contractions of the soleus muscle had been depressed by excess K+, depletion of K+ or by ouabain, terbutaline restored the twitch tension. It is suggested that the contractile machinery of the muscles is controlled by the ionic balance which in turn is changed following beta-adrenoceptor stimulation.

Changes in skeletal muscle glycogenolysis after prolonged cold exposure and repeated injections with isoproterenol

Wistar rats were either given daily injections of isoproterenol (ISO) (15 μg/100 g per day) or exposed to 6 °C for 4 or 12 weeks (cold acclimated (CA)). After a 4-week exposure to cold and to ISO, acute cold stress (4 h at –18 °C) produced a 48% depletion of glycogen in the tibialis anterior of control rats while it did not significantly affect the levels in ISO-treated and CA animals. ISO treatment enhanced the in vivo response of phosphorylase kinase and glycogen phosphorylase to epinephrine (EPI) in the tibialis anterior, a fast contracting muscle. In the soleus, a slow contracting muscle known to be more sensitive to catecholamines, chronic treatment with ISO also resulted in increased basal and EPI-stimulated adenylate cyclase activity. No evidence could be found for an alteration of the glycogenolytic pathway (adenylate cyclase system, phosphorylase kinase, and glycogen phosphorylase) in fast contracting skeletal muscles of CA rats. It is concluded that ISO-treated and CA rats, which have a great capacity for nonshivering thermogenesis, do not rely on their muscle carbohydrate reserves during cold stress. It might be suggested that plasma levels of catecholamines higher than those produced by exposure to 6 °C are required to alter glycogenolytic mechanisms in fast contracting rat skeletal muscles.

Pentobarbitone and skeletal muscle contractions: on the interaction with the effect elicited by the beta-adrenoceptor agonist, terbutaline.

The soleus, a slow-contracting muscle, and the extensor digitorum longus (EDL), a fast-contracting muscle from guinea-pig were prepared for isometric recording in vitro. Subtetanic contractions were evoked by transmural field-stimulation. Pentobarbitone increased the force of contraction in both muscles. In the soleus it shifted the stimulation frequency-response curve to the left. Terbutaline caused a decrease in the force of subtetanic contractions of the soleus, an effect which was dependent on the stimulation frequency. In the presence of pentobarbitone, the stimulation frequency had to be lowered by about 2 HZ in order to maintain the optimum response to terbutaline. The EDL responded to terbutaline with an increased force of contraction. In this case the stimulation frequency was less critical and the effects were the same in the presence and in the absence of pentobarbitone. Experiments with alpha-chloralose yielded results similar to those obtained with pentobarbitone.

Correlation between the effects of salbutamol on contractions and cyclic AMP content of isolated fast ? and slow ? contracting muscles of the guinea pig

The effects of isoprenaline and salbutamol on incomplete tetanic contractions of the isolated soleus (slow contracting) and extensor digitorum longus (EDL-fast-contracting) muscles of the guinea pig were studied and an attempt made to correlate these effects on contractility with changes in cyclic AMP concentrations. Salbutamol was 10-12 times less potent than (+/-)isoprenaline in decreasing the force of subtetanic contractions in the soleus and between 5-6 times less potent in increasing the force of subtetanic contractions in the EDL. This observation plus the lack of activity of both the selective beta1-adrenoceptor antagonist (atenolol) and the selective beta1 agonist (H 133/22) in the EDL implies involvement of beta2-adrenoceptors in these responses of the muscles to isoprenaline and salbutamol. The soleus muscle was about 6-12 times more sensitive to effects of beta-adrenoceptor agonists than the EDL. In concentrations which produced effects on muscle contractility, salbutamol significantly elevated cyclic AMP concentrations in both types of muscle. These effects were antagonised by propranolol. It seems clear that the contrasting effects of sympathomimetic amines on slow-and fast contracting muscle are mediated through a common mechanism-elevation of cyclic AMP. Possible explanations of this apparent paradox are discussed.