Frog Gastrocnemius Research Articles

Study on Anti-fatigue Effects and Mechanisms of Polysaccharide from Paris polyphylla.

The objectives of this study were to investigate the anti-fatigue effects of Paris polyphylla polysaccharide component 1 (PPPm-1) and explore its mechanisms. A mouse model of exercise-induced fatigue was established by weight-bearing swimming to observe the effects of different concentrations of PPPm-1 on weight-bearing swimming time. The anti-fatigue effect of PPPm-1 was determined by the effects of contraction amplitude, contraction rate, and diastolic rate of the frog gastrocnemius muscle in vivo before and after infiltration with 5 mg/mL PPPm-1. The effects of PPPm-1 on the contents of blood lactate, serum urea nitrogen, hepatic glycogen, muscle glycogen in the exercise fatigue model of mice, and acetylcholine (ACh) content and acetylcholinesterase (AChE) activity at the junction of the frog sciatic nerve-gastrocnemius under normal physiological, and Na+-K+-ATPase and Ca2+-Mg2+-ATPase activities of the frog gastrocnemius were determined by enzyme-linked immunosorbent assay (ELISA), to investigate the anti-fatigue mechanisms of PPPm-1. The results showed that PPPm-1 could significantly prolong the weight-bearing swimming time in mice (P < 0.01), decrease the contents of blood lactate and serum urea nitrogen, increase the contents of the hepatic glycogen and muscle glycogen of mice after exercise fatigue compared with those of the control group, and there was extremely significant difference in most indicators (P < 0.01). The 5mg/mL of PPPm-1 could significantly promote the contraction amplitude, contraction rate, and relaxation rate of the gastrocnemius muscle in the frogs, and the content of ACh at the junction of the frog sciatic nerve-gastrocnemius (P < 0.01), but it had obvious inhibitory effetc on the activity of AChE at the junction of the frog sciatic nerve-gastrocnemius (P < 0.01). PPPm-1 could increase the Na+-K+-ATPase and Ca2+-Mg2+-ATPase activities of gastrocnemius in the frogs (for Ca2+-Mg2+-ATPase, P < 0.01). The above results suggested that the PPPm-1 had a good anti-fatigue effect, and its main mechanisms were related to improving endurance and glycogen reserve, reducing glycogen consumption, lactate and serum urea nitrogen accumulation, and promoting Ca2+ influx.

Effect of khat leaves extract (Catha edulis) on the excitability of frog gastrocnemius.

This study was held on the isolated excitable tissue of frog's gastrocnemius muscle. Experiments were down by determining the dose dependent of leaves of khat extract. Work down in accordance with personal presupposition since reported that khat have psycho stimulant effects accordingly we thought khat might have effects on systemically biology that mediated by chticol amines. Results showed the effect of khat leaves extract on excitability of muscle contraction that was easily attested when the electrical stimuli were applied either through the nerve or directly to the muscle. Whereas khat treatment showed a significant increase in the contraction period of the gastrocnemius muscle and both of the relaxation periods and half relaxation time were shortened. Also it was found that pretreatment by khat leaves extract caused changes in the tension output, increased the height of effect intensity with prolonged the contraction period, while the latent period was decreased and reduced slightly the half relaxation period of the twitch comparison with the normal control muscle. These experimental results indicated that khat had highly stimulant effects on muscle, whereas caused liberation of thermoenzymatic and chemical energy during contraction which converted into mechanical energy, which manifested its self as work.

BK channel openers NS1619 and NS11021 reverse hydrogen peroxide-induced membrane potential changes in skeletal muscle

Large conductance calcium-activated potassium (BK) channels play a crucial role in the repolarization and after-hyperpolarization phases of the cell membrane. The channel openers are also used in treatment of some diseases, including hypo/hyperkalemic periodic paralysis. However, little is known about the effects of BK channels and the channel activators on membrane potentials in skeletal muscle. In addition, the effects of reactive oxygen species (ROS) on BK channels in skeletal muscle are also unknown. Therefore, the aim of this study was to determine the effects of BK channel openers and ROS on membrane potentials in skeletal muscle fibers. For this purpose, resting membrane potentials and action potentials (AP) of frog gastrocnemius muscles were recorded in the presence of commonly used BK channel openers NS1619 and NS11021, H2O2 (a type of ROS), and both using intracellular microelectrode technique. The channel activators significantly and dose-dependently decreased amplitude and increased rise time of AP but did not impact repolarization. The presence of H2O2 plus NS1619 or NS11021 resulted in significant change because the channel openers completely reversed the deleterious effects of hydrogen peroxide on the repolarization phase of AP in skeletal muscle fibers. In the present study, the contributions of BK channel activation and the modulatory role of H2O2 on membrane potentials was demonstrated in skeletal muscle fibers, for the first time. Moreover, it should be noted that BK channel openers should be used in the treatment of reactive oxygen species-induced skeletal muscle diseases.

Leveraging artificial neural networks to mesh frog gastrocnemius muscle from digital photography

ABSTRACTThere has been a lot of development in realistic muscle modeling based on finite elements in the last decade. However, one of the challenges in this area remains to be custom or specimen-specific meshing of the relevant muscle, mainly due to the scarcity of the DT-MRI infrastructure and expertise. The purpose of this work is to capitalize on the Bayesian regularization backpropagation based artificial neural networks, to transform digital photographic imagery into a finite element mesh, and the accompanying internal fiber orientation data. A gastrocnemius muscle was extracted from a frog and utilized to conduct the proposed work. Due to the highly nonlinear nature of the resulting finite element model, from both metric and material considerations, as well as the limited suitability of available elements for meshing in this case, a custom hexahedral-type mesh topology was selected for the meshing procedure. Results indicate a very good agreement between the geometries of the sample muscle and its mesh. Furthermore, fiber orientations were approximated as following the fusiform geometry of the muscle. The proposed framework can be used to overcome the pre-processing requirements of subject-specific muscles, including hexahedral-type meshing and extraction of internal fiber orientation data.

Cordycepin depresses the skeletal muscle contraction of toad gastrocnemius muscle involving Ca2+-dependent mechanisms

This study was carried out to investigate the modulation effect of cordycepin on the skeletal muscle contractile performance and its potential mechanisms involving interaction between cordycepin and Ca2+ by electrical field stimulation. Results showed that cordycepin (50 mg L−1) significantly decreased the muscle contractile response reversibly. Cordycepin also produced a rightward shift of the contractile amplitude–stimulation intensity relationship. However, the most noticeable result was that the maximum amplitude of the muscle contractile force was significantly increased under cordycepin application (119 ± 5·6% of control). This result suggests that the skeletal muscle contractile function and muscle physical fitness to the external stimulation were improved by the decreased response sensitivity in the presence of cordycepin. However, these improved effects of cordycepin on muscle physical performance were diminished in Ca2+-free medium or in the presence of all Ca2+ channels blocker (0·4 mM CdCl2). These results suggest that cordycepin can positively affect skeletal muscle physical performance involving Ca2+-dependent mechanisms.

Modulation effects of cordycepin on the skeletal muscle contraction of toad gastrocnemius muscle

Isolated toad gastrocnemius muscle is a typical skeletal muscle tissue that is frequently used to study the motor system because it is an important component of the motor system. This study investigates the effects of cordycepin on the skeletal muscle contractile function of isolated toad gastrocnemius muscles by electrical field stimulation. Results showed that cordycepin (20mg/l to 100mg/l) significantly decreased the contractile responses in a concentration-dependent manner. Cordycepin (50mg/l) also produced a rightward shift of the contractile amplitude-stimulation intensity relationship, as indicated by the increases in the threshold stimulation intensity and the saturation stimulation intensity. However, the most notable result was that the maximum amplitude of the muscle contractile force was significantly increased under cordycepin application (122±3.4% of control). This result suggests that the skeletal muscle contractile function and muscle physical fitness to the external stimulation were improved by the decreased response sensitivity in the presence of cordycepin. Moreover, cordycepin also prevented the repetitive stimulation-induced decrease in muscle contractile force and increased the recovery amplitude and recovery ratio of muscle contraction. However, these anti-fatigue effects of cordycepin on muscle contraction during long-lasting muscle activity were absent in Ca2+-free medium or in the presence of all Ca2+ channels blocker (0.4mM CdCl2). These results suggest that cordycepin can positively affect muscle performance and provide ergogenic and prophylactic benefits in decreasing skeletal muscle fatigue. The mechanisms involving excitation-coupled Ca2+ influxes are strongly recommended.

Some Pharmacodynamic Aspects of Cefepime.

Some pharmacodynamic effects of cefepime, a new injectable semisynthetic cephalosporin, were studied in laboratory animals and the following results were obtained. Cefepime maximally stimulated isolated guinea pig's ileum, rat's colon (80 μg/mL bath), and rabbit's duodenum (400 μg/mL bath). Contrarily, complete relaxation of isolated rat's fundic strip was produced by 80 μg/mL bath. Effects of cefepime on isolated rat's uterine muscle were different according to stage of sex cycle. Cefepime did not induce any effects on the resting tonus of isolated guinea pig's tracheal chain and rabbit's aortic strip. Concentrations of 200 and 400 μg/mL bath induced marked inhibition in the force of muscular twitches of the isolated frog's gastrocnemius muscle which was less potent than that induced by procaine hydrochloride 2%. Cefepime completely blocked the neuromuscular transmission of frog's rectus abdominis muscle (40 μg/mL bath) and rat's phrenic nerve hemidiaphragm preparation (200 μg/mL bath). This blockade was reversed by acetylcholine and neostigmine. Cefepime produced dose-dependent negative inotropic effect on isolated rabbit's heart and guinea pig's auricles. There were no changes in blood pressure and rate of respiration in anaesthetized dog after cefepime injection. These findings indicate that cefepime has a low potential to produce adverse reactions at therapeutic doses.

Functional Electrical Stimulation by Nanogenerator with 58 V Output Voltage

We demonstrate a new type of integrated nanogenerator based on arrays of vertically aligned piezoelectric ZnO nanowires. The peak open-circuit voltage and short-circuit current reach a record high level of 58 V and 134 μA, respectively, with a maximum power density of 0.78 W/cm(3). The electric output was directly applied to a sciatic nerve of a frog, inducing innervation of the nerve. Vibrant contraction of the frog's gastrocnemius muscle is observed as a result of the instantaneous electric input from the nanogenerator.

Effects of Low-Power Pulsed Laser Irradiation on Muscle Contraction of Frog Gastrocnemius

Effects of Low-Power Pulsed Laser Irradiation on Muscle Contraction of Frog Gastrocnemius

Association of muscle hardness with muscle tension dynamics: a physiological property

This study aimed to investigate the relationship between muscle hardness and muscle tension in terms of length-tension relationship. A frog gastrocnemius muscle sample was horizontally mounted on the base plate inside a chamber and was stretched from 100 to 150% of the pre-length, in 5% increments. After each step of muscle lengthening, electrical field stimulation for induction of tetanus was applied using platinum-plate electrodes positioned on either side of the muscle submerged in Ringer's solution. The measurement of muscle hardness, i.e., applying perpendicular distortion, was performed whilst maintaining the plateau of passive and tetanic tension. The relationship between normalised tension and normalised muscle hardness was evaluated. The length-hardness diagram could be created from the modification with the length-tension diagram. It is noteworthy that muscle hardness was proportional to passive and total tension. Regression analysis revealed a significant correlation between muscle hardness and passive and total tension, with a significant positive slope (passive tension: r = 0.986, P < 0.001; total tension: r = 0.856, P < 0.001). In conclusion, our results suggest that muscle hardness depends on muscle tension in most ranges of muscle length in the length-tension diagram.

Inhibition of cholinergic response by taurine in frog isolated skeletal muscle.

Carbamylcholine-stimulated contractions of isolated frog gastrocnemius muscle were inhibited in a non-competitive fashion by 5-25 mM taurine. Taurine had no effect on the resting length of the muscle. Caffeine-induced contractures were unaffected by taurine which indicates that the sarcoplasmic reticulum is not an important site of action for taurine. A possible functional role for taurine in skeletal muscle is discussed.

Effects of 405/532/808 nm low-power laser irradiation on the muscle contraction of frog gastrocnemius

Effects of 405/532/808 nm low-power laser irradiation on the muscle contraction of frog gastrocnemius

Transverse relaxation and magnetization transfer in skeletal muscle: Effect of pH

Exercise increases the intracellular T(2) (T(2,i)) of contracting muscles. The mechanism(s) for the T(2,i) increase have not been fully described, and may include increased intracellular free water and acidification. These changes may alter chemical exchange processes between intracellular free water and proteins. In this study, the hypotheses were tested that (a) pH changes T(2,i) by affecting the rate of magnetization transfer (MT) between free intracellular water and intracellular proteins, and (b) the magnitude of the T(2,i) effect depends on acquisition mode (localized or nonlocalized) and echo spacing. Frog gastrocnemius muscles were excised and their intracellular pH was either kept at physiological pH (7.0) or modified to model exercising muscle (pH 6.5). The intracellular transverse relaxation rate (R(2,i) = 1/T(2,i)) always decreased in the acidic muscles, but the changes were greater when measured using more rapid refocusing rates. The MT rate from the macromolecular proton pool to the free water proton pool, its reverse rate, and the spin-lattice relaxation rate of water decreased in acidic muscles. It is concluded that intracellular acidification alters the R(2,i) of muscle water in a refocusing rate-dependent manner, and that the R(2,i) changes are correlated with changes in the MT rate between macromolecules and free intracellular water.

Effects of 808 nm low‐power laser irradiation on the muscle contraction of frog gastrocnemius

The efficacy of low-power laser irradiation (LLI) on muscle fibers remains unclear; therefore, we examined the effect of LLI (808 nm: 60 or 100 mW) on muscle contraction and conducted waveform analyses of the twitch curve, including alterations in the peak amplitudes of tension (AMP), latency (LAT), contraction period (CP), and relaxation period (RP). The sciatic nerve-gastrocnemius muscles of 35 frogs (Xenopus laevis) were prepared. In Experiment 1, continuous stimulation for gastrocnemius contraction was delivered to the sciatic nerve (10 minutes); the experimental group simultaneously received LLI. In Experiment 2, two sets of stimulation and cessation (2 minutes each) were repeated after the initial stimulation period (2 minutes); the experimental group received LLI during the resting period. In Experiment 1, 60 mW LLI significantly facilitated an attenuation of AMP and maintained a smaller prolongation of CP (P<0.05), whereas 100 mW LLI significantly influenced a retardation of AMP attenuation and LAT prolongation (P<0.05). In Experiment 2, 100 mW LLI significantly influenced AMP attenuation and LAT prolongation by retardation (P<0.05); almost no effects were obtained in the case of 60 mW LLI. These results suggest that 808 nm LLI influences both synaptic signal transmission at the neuromuscular junction and excitation-contraction coupling in the muscle fibers, but not the relaxation process. We conclude that LLI at relatively high doses can influence muscle by retarding AMP attenuation and LAT prolongation.

Fractional Multi-models of the Frog Gastrocnemius Muscle

In this article, frog gastrocnemius muscles are studied, and a multi-model identification presented. A transfer function is defined with few parameters to simulate striated muscle (Gastroctnemius) behaviour, for inclusion in a future real-time salamander computer model. A two-model structure permits description of both contraction and relaxation properties. Here, two physiological influences, fatigue and fibre types, are taken into account. A multi-model structure for each fibre type (fast (IIB), intermediate (IIA) and slow (I) fibres) is also used for inclusion in a future agonist-antagonist structure computer model.

Finite element modelling of skeletal muscles coupled with fatigue

In this study, Hill's muscle theory coupled with fatigue was proposed to describe mechanical behaviours of skeletal muscles. The force developed by a fatigued muscle was described by a muscle fatigue formula which was a time function of the activation α a and the stretch λ. The modified Hill's muscle theory was hence incorporated into a three-dimensional (3D) finite element model using the PAK finite element code. In this paper, the theoretical derivation of the 3D muscle model was firstly described. After presenting the method of establishing the finite element programme, a case example of studying the mechanical response of a frog gastrocnemius muscle was used to illustrate the applicability of the proposed methodology. The effects of the muscle fatigue on the deformation as well as the stress and strain distribution of the frog muscle subject to a cyclic activation function have been determined. An experiment capturing the real-time shape change of a frog muscle was also conducted to assess the applicability of the proposed method. A comparison between the deformed shapes of the predictive model and the frog muscles was also made. It was shown that the method is capable of providing a reasonable model for describing the mechanical behaviour of skeletal muscles.

Effects of low power laser irradiation on muscle contraction of the frog gastrocnemius

Effects of low power laser irradiation on muscle contraction of the frog gastrocnemius

Modeling force–velocity relation in skeletal muscle isotonic contraction using an artificial neural network

The aim of this study is to design an artificial neural network (ANN) to model force–velocity relation in skeletal muscle isotonic contraction. We obtained the data set, including physiological and morphometric parameters, by myography and morphometric measurements on frog gastrocnemius muscle. Then, we designed a multilayer perceptron ANN, the inputs of which are muscle volume, muscle optimum length, tendon length, preload, and afterload. The output of the ANN is contraction velocity. The experimental data were divided randomly into two parts. The fisrt part was used to train the ANN. In order to validate the model, the second part of experimental data, which was not used in training, was employed to the ANN and then, its output was compared with Hill model and the experimental data. The behavior of ANN in high forces was more similar to experimental data, but in low forces the Hill model had better results. Furthermore, extrapolation of ANN performance showed that our model is more or less able to simulate eccentric contraction. Our results indicate that ANNs represent a powerful tool to capture some essential features of muscle isotonic contraction.

A neurotoxic phospholipase A 2 variant: Isolation and characterization from eastern regional Indian cobra ( Naja naja) venom

CM-Sephadex C-25 column chromatography profile of Indian cobra ( Naja naja) venom from eastern region showed a distinct and a dominant phospholipase peak, peak-10, while it was not seen in either southern or western venom samples. Peak-10 was subjected to CM-Sephadex C-25 and Sephadex G-50 column chromatography to isolate NN-X-PLA 2. NN-X-PLA 2 is a single chain protein with the relative molecular weight of 10 kDa by SDS-PAGE. It was toxic to mice with an LD 50 value 0.098 mg/kg body weight (i.p.) and the mice exhibited acute neurotoxic symptoms. Upon indirect stimulation, it inhibited the twitching of frog's gastrocnemius muscle in a dose dependent manner. NN-X-PLA 2 was weakly anticoagulant and devoid of cytotoxicity, myotoxicity, hemorrhage, edema inducing, and directlytic activities and effects on platelet aggregation process. Upon chemical modification independently with p-bromophenacyl bromide and acetic anhydride, NN-X-PLA 2 lost both enzymatic and toxic properties.

FRACTIONAL MULTI-MODELS OF THE GASTROCNEMIUS FROG MUSCLE

Frog gastrocnemius muscles are studied, and a multi-model identification presented. A transfer function is here defined with few parameters to simulate striated muscle (Gastroctnemius) behaviour, for inclusion in a future real-time salamander computer model. A two-model structure permits description of both contraction and relaxation properties. Here, two physiological influences, fatigue and fibre types, are taken into account. A multi-model structure for each fibre type (Fast (IIB), Intermediate (IIA) and Slow (I) fibres) is also used for inclusion in a future agonist-antagonist structure computer model.