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Urs T. Ruegg - One of the best experts on this subject based on the ideXlab platform.

  • Mdx myotubes have normal excitability but show reduced contraction–relaxation dynamics
    Journal of Muscle Research & Cell Motility, 2001
    Co-Authors: Valerie Nicolas-metral, Eric Raddatz, Pavel Kucera, Urs T. Ruegg
    Abstract:

    The pathogenesis of Duchenne muscular dystrophy (DMD), characterised by lack of the cytoskeletal protein dystrophin, is not completely understood. An early event in the degenerative process of DMD muscle could be a rise in cytosolic calcium concentration. In order to investigate whether this leads to alterations of contractile behaviour, we studied the excitability and contractile properties of cultured myotubes from control (C57BL/10) and mdx mice, an animal model for DMD. The myotubes were stimulated electrically and their motion was recorded photometrically. No significant differences were found between control and mdx myotubes with respect to the following parameters: Chronaxy and rheobase (0.33 ± 0.03 ms and 23 ± 4 V vs. 0.39 ± 0.07 ms and 22 ± 2 V for C57 and mdx myotubes, respectively), tetanisation frequency (a similar distribution pattern was found between 5 and 30 Hz), fatigue during tetanus (found in 35% of both types of myotubes) and post-tetanic contracture. In contrast, contraction and relaxation times were longer ( P < 0.005) in mdx (36 ± 2 and 142 ± 13 ms, respectively) than in control myotubes (26 ± 1 and 85 ± 9 ms, respectively). Together with our earlier findings, these results suggest a decreased capacity for calcium removal in mdx cells leading, in particular, to alterations of muscle relaxation.

  • Mdx myotubes have normal excitability but show reduced contraction-relaxation dynamics.
    Journal of Muscle Research and Cell Motility, 2001
    Co-Authors: Valerie Nicolas-metral, Eric Raddatz, Pavel Kucera, Urs T. Ruegg
    Abstract:

    The pathogenesis of Duchenne muscular dystrophy (DMD), characterised by lack of the cytoskeletal protein dystrophin, is not completely understood. An early event in the degenerative process of DMD muscle could be a rise in cytosolic calcium concentration. In order to investigate whether this leads to alterations of contractile behaviour, we studied the excitability and contractile properties of cultured myotubes from control (C57BL/10) and mdx mice, an animal model for DMD. The myotubes were stimulated electrically and their motion was recorded photometrically. No significant differences were found between control and mdx myotubes with respect to the following parameters: Chronaxy and rheobase (0.33 ± 0.03 ms and 23 ± 4 V vs. 0.39 ± 0.07 ms and 22 ± 2 V for C57 and mdx myotubes, respectively), tetanisation frequency (a similar distribution pattern was found between 5 and 30 Hz), fatigue during tetanus (found in 35% of both types of myotubes) and post-tetanic contracture. In contrast, contraction and relaxation times were longer (P < 0.005) in mdx (36 ± 2 and 142 ± 13 ms, respectively) than in control myotubes (26 ± 1 and 85 ± 9 ms, respectively). Together with our earlier findings, these results suggest a decreased capacity for calcium removal in mdx cells leading, in particular, to alterations of muscle relaxation.

Valerie Nicolas-metral - One of the best experts on this subject based on the ideXlab platform.

  • Mdx myotubes have normal excitability but show reduced contraction–relaxation dynamics
    Journal of Muscle Research & Cell Motility, 2001
    Co-Authors: Valerie Nicolas-metral, Eric Raddatz, Pavel Kucera, Urs T. Ruegg
    Abstract:

    The pathogenesis of Duchenne muscular dystrophy (DMD), characterised by lack of the cytoskeletal protein dystrophin, is not completely understood. An early event in the degenerative process of DMD muscle could be a rise in cytosolic calcium concentration. In order to investigate whether this leads to alterations of contractile behaviour, we studied the excitability and contractile properties of cultured myotubes from control (C57BL/10) and mdx mice, an animal model for DMD. The myotubes were stimulated electrically and their motion was recorded photometrically. No significant differences were found between control and mdx myotubes with respect to the following parameters: Chronaxy and rheobase (0.33 ± 0.03 ms and 23 ± 4 V vs. 0.39 ± 0.07 ms and 22 ± 2 V for C57 and mdx myotubes, respectively), tetanisation frequency (a similar distribution pattern was found between 5 and 30 Hz), fatigue during tetanus (found in 35% of both types of myotubes) and post-tetanic contracture. In contrast, contraction and relaxation times were longer ( P < 0.005) in mdx (36 ± 2 and 142 ± 13 ms, respectively) than in control myotubes (26 ± 1 and 85 ± 9 ms, respectively). Together with our earlier findings, these results suggest a decreased capacity for calcium removal in mdx cells leading, in particular, to alterations of muscle relaxation.

  • Mdx myotubes have normal excitability but show reduced contraction-relaxation dynamics.
    Journal of Muscle Research and Cell Motility, 2001
    Co-Authors: Valerie Nicolas-metral, Eric Raddatz, Pavel Kucera, Urs T. Ruegg
    Abstract:

    The pathogenesis of Duchenne muscular dystrophy (DMD), characterised by lack of the cytoskeletal protein dystrophin, is not completely understood. An early event in the degenerative process of DMD muscle could be a rise in cytosolic calcium concentration. In order to investigate whether this leads to alterations of contractile behaviour, we studied the excitability and contractile properties of cultured myotubes from control (C57BL/10) and mdx mice, an animal model for DMD. The myotubes were stimulated electrically and their motion was recorded photometrically. No significant differences were found between control and mdx myotubes with respect to the following parameters: Chronaxy and rheobase (0.33 ± 0.03 ms and 23 ± 4 V vs. 0.39 ± 0.07 ms and 22 ± 2 V for C57 and mdx myotubes, respectively), tetanisation frequency (a similar distribution pattern was found between 5 and 30 Hz), fatigue during tetanus (found in 35% of both types of myotubes) and post-tetanic contracture. In contrast, contraction and relaxation times were longer (P < 0.005) in mdx (36 ± 2 and 142 ± 13 ms, respectively) than in control myotubes (26 ± 1 and 85 ± 9 ms, respectively). Together with our earlier findings, these results suggest a decreased capacity for calcium removal in mdx cells leading, in particular, to alterations of muscle relaxation.

Eric Raddatz - One of the best experts on this subject based on the ideXlab platform.

  • Mdx myotubes have normal excitability but show reduced contraction–relaxation dynamics
    Journal of Muscle Research & Cell Motility, 2001
    Co-Authors: Valerie Nicolas-metral, Eric Raddatz, Pavel Kucera, Urs T. Ruegg
    Abstract:

    The pathogenesis of Duchenne muscular dystrophy (DMD), characterised by lack of the cytoskeletal protein dystrophin, is not completely understood. An early event in the degenerative process of DMD muscle could be a rise in cytosolic calcium concentration. In order to investigate whether this leads to alterations of contractile behaviour, we studied the excitability and contractile properties of cultured myotubes from control (C57BL/10) and mdx mice, an animal model for DMD. The myotubes were stimulated electrically and their motion was recorded photometrically. No significant differences were found between control and mdx myotubes with respect to the following parameters: Chronaxy and rheobase (0.33 ± 0.03 ms and 23 ± 4 V vs. 0.39 ± 0.07 ms and 22 ± 2 V for C57 and mdx myotubes, respectively), tetanisation frequency (a similar distribution pattern was found between 5 and 30 Hz), fatigue during tetanus (found in 35% of both types of myotubes) and post-tetanic contracture. In contrast, contraction and relaxation times were longer ( P < 0.005) in mdx (36 ± 2 and 142 ± 13 ms, respectively) than in control myotubes (26 ± 1 and 85 ± 9 ms, respectively). Together with our earlier findings, these results suggest a decreased capacity for calcium removal in mdx cells leading, in particular, to alterations of muscle relaxation.

  • Mdx myotubes have normal excitability but show reduced contraction-relaxation dynamics.
    Journal of Muscle Research and Cell Motility, 2001
    Co-Authors: Valerie Nicolas-metral, Eric Raddatz, Pavel Kucera, Urs T. Ruegg
    Abstract:

    The pathogenesis of Duchenne muscular dystrophy (DMD), characterised by lack of the cytoskeletal protein dystrophin, is not completely understood. An early event in the degenerative process of DMD muscle could be a rise in cytosolic calcium concentration. In order to investigate whether this leads to alterations of contractile behaviour, we studied the excitability and contractile properties of cultured myotubes from control (C57BL/10) and mdx mice, an animal model for DMD. The myotubes were stimulated electrically and their motion was recorded photometrically. No significant differences were found between control and mdx myotubes with respect to the following parameters: Chronaxy and rheobase (0.33 ± 0.03 ms and 23 ± 4 V vs. 0.39 ± 0.07 ms and 22 ± 2 V for C57 and mdx myotubes, respectively), tetanisation frequency (a similar distribution pattern was found between 5 and 30 Hz), fatigue during tetanus (found in 35% of both types of myotubes) and post-tetanic contracture. In contrast, contraction and relaxation times were longer (P < 0.005) in mdx (36 ± 2 and 142 ± 13 ms, respectively) than in control myotubes (26 ± 1 and 85 ± 9 ms, respectively). Together with our earlier findings, these results suggest a decreased capacity for calcium removal in mdx cells leading, in particular, to alterations of muscle relaxation.

Pavel Kucera - One of the best experts on this subject based on the ideXlab platform.

  • Mdx myotubes have normal excitability but show reduced contraction–relaxation dynamics
    Journal of Muscle Research & Cell Motility, 2001
    Co-Authors: Valerie Nicolas-metral, Eric Raddatz, Pavel Kucera, Urs T. Ruegg
    Abstract:

    The pathogenesis of Duchenne muscular dystrophy (DMD), characterised by lack of the cytoskeletal protein dystrophin, is not completely understood. An early event in the degenerative process of DMD muscle could be a rise in cytosolic calcium concentration. In order to investigate whether this leads to alterations of contractile behaviour, we studied the excitability and contractile properties of cultured myotubes from control (C57BL/10) and mdx mice, an animal model for DMD. The myotubes were stimulated electrically and their motion was recorded photometrically. No significant differences were found between control and mdx myotubes with respect to the following parameters: Chronaxy and rheobase (0.33 ± 0.03 ms and 23 ± 4 V vs. 0.39 ± 0.07 ms and 22 ± 2 V for C57 and mdx myotubes, respectively), tetanisation frequency (a similar distribution pattern was found between 5 and 30 Hz), fatigue during tetanus (found in 35% of both types of myotubes) and post-tetanic contracture. In contrast, contraction and relaxation times were longer ( P < 0.005) in mdx (36 ± 2 and 142 ± 13 ms, respectively) than in control myotubes (26 ± 1 and 85 ± 9 ms, respectively). Together with our earlier findings, these results suggest a decreased capacity for calcium removal in mdx cells leading, in particular, to alterations of muscle relaxation.

  • Mdx myotubes have normal excitability but show reduced contraction-relaxation dynamics.
    Journal of Muscle Research and Cell Motility, 2001
    Co-Authors: Valerie Nicolas-metral, Eric Raddatz, Pavel Kucera, Urs T. Ruegg
    Abstract:

    The pathogenesis of Duchenne muscular dystrophy (DMD), characterised by lack of the cytoskeletal protein dystrophin, is not completely understood. An early event in the degenerative process of DMD muscle could be a rise in cytosolic calcium concentration. In order to investigate whether this leads to alterations of contractile behaviour, we studied the excitability and contractile properties of cultured myotubes from control (C57BL/10) and mdx mice, an animal model for DMD. The myotubes were stimulated electrically and their motion was recorded photometrically. No significant differences were found between control and mdx myotubes with respect to the following parameters: Chronaxy and rheobase (0.33 ± 0.03 ms and 23 ± 4 V vs. 0.39 ± 0.07 ms and 22 ± 2 V for C57 and mdx myotubes, respectively), tetanisation frequency (a similar distribution pattern was found between 5 and 30 Hz), fatigue during tetanus (found in 35% of both types of myotubes) and post-tetanic contracture. In contrast, contraction and relaxation times were longer (P < 0.005) in mdx (36 ± 2 and 142 ± 13 ms, respectively) than in control myotubes (26 ± 1 and 85 ± 9 ms, respectively). Together with our earlier findings, these results suggest a decreased capacity for calcium removal in mdx cells leading, in particular, to alterations of muscle relaxation.

José Henrique Leal-cardoso - One of the best experts on this subject based on the ideXlab platform.

  • Essential oil of Lippia alba and its main constituent citral block the excitability of rat sciatic nerves
    Brazilian Journal of Medical and Biological Research, 2015
    Co-Authors: D.g. Sousa, José Henrique Leal-cardoso, S.d.g. Sousa, R.e.r. Silva, K.s. Silva-alves, F.w. Ferreira-da-silva, Marta Regina Kerntopf, Irwin Rose Alencar De Menezes, Roseli Barbosa
    Abstract:

    Lippia alba is empirically used for infusions, teas, macerates, and hydroalcoholic extracts because of its antispasmodic, analgesic, sedative, and anxiolytic effects. Citral is a mixture of trans-geranial and cis-neral and is the main constituent of L. alba essential oil and possesses analgesic, anxiolytic, anticonvulsant, and sedative effects. The present study evaluated the effects of the essential oil of L. alba (EOLa) and citral on compound action potentials (CAPs) in Wistar rat sciatic nerves. Both drugs inhibited CAP in a concentration-dependent manner. The calculated half-maximal inhibitory concentrations (IC50) of peak-to-peak amplitude were 53.2 µg/mL and 35.00 µg/mL (or 230 µM) for EOLa and citral, respectively. Peak-to-peak amplitude of the CAP was significantly reduced by 30 µg/mL EOLa and 10 µg/mL citral. EOLa and citral (at 60 and 30 µg/mL, values close to their respective IC50 for CAP blockade) significantly increased Chronaxy and rheobase. The conduction velocity of the first and second CAP components was statistically reduced to ∼86% of control with 10 µg/mL EOLa and ∼90% of control with 3 µg/mL citral. This study showed that EOLa inhibited nerve excitability and this effect can be explained by the presence of citral in its composition. Both EOLa and citral showed inhibitory actions at lower concentrations compared with other essential oils and constituents with local anesthetic activity. In conclusion, these data demonstrate that EOLa and citral are promising agents in the development of new drugs with local anesthetic activity.

  • Limb immobilization alters functional electrophysiological parameters of sciatic nerve
    Brazilian Journal of Medical and Biological Research, 2013
    Co-Authors: Jamille Soares Moreira Alves, José Henrique Leal-cardoso, Francisco Fleury Uchôa Santos-júnior, P.s. Carlos, Renata Carvalho Silva, Carolina Madeira Lucci, Sônia Nair Báo, Vânia Marilande Ceccatto, Roseli Barbosa
    Abstract:

    Immobilization, used in clinical practice to treat traumatologic problems, causes changes in muscle, but it is not known whether changes also occur in nerves. We investigated the effects of immobilization on excitability and compound action potential (CAP) and the ultrastructure of the rat sciatic nerve. Fourteen days after immobilization of the right leg of adult male Wistar rats (n=34), animals were killed and the right sciatic nerve was dissected and mounted in a moist chamber. Nerves were stimulated at a baseline frequency of 0.2 Hz and tested for 2 min at 20, 50, and 100 Hz. Immobilization altered nerve excitability. Rheobase and Chronaxy changed from 3.13±0.05 V and 52.31±1.95 µs (control group, n=13) to 2.84±0.06 V and 59.71±2.79 µs (immobilized group, n=15), respectively. Immobilization altered the amplitude of CAP waves and decreased the conduction velocity of the first CAP wave (from 93.63±7.49 to 79.14±5.59 m/s) but not of the second wave. Transmission electron microscopy showed fragmentation of the myelin sheath of the sciatic nerve of immobilized limbs and degeneration of the axon. In conclusion, we demonstrated that long-lasting leg immobilization can induce alterations in nerve function.

  • Carvacrol Decreases Neuronal Excitability by Inhibition of Voltage-Gated Sodium Channels
    Journal of Natural Products, 2012
    Co-Authors: Humberto Cavalcante Joca, Telma L G Lemos, Paulo Beirão, Yuri Cruz-mendes, Klausen Oliveira-abreu, Rebeca Peres Moreno Maia-joca, Roseli Barbosa, José Henrique Leal-cardoso
    Abstract:

    The monoterpenoid carvacrol (1) is present in many essential oils of plants and has attracted attention because of its beneficial biological activities, especially analgesic activity. However, the mechanism of action of 1 remains unknown. The present study aimed to explore the mechanisms whereby 1 produces its effects on the peripheral nervous system. Carvacrol reversibly blocked the excitability of the rat sciatic nerve in a concentration-dependent manner with an IC50 value of 0.50 ± 0.04 mM. At 0.6 mM, 1 increased the rheobase from 3.30 ± 0.06 V to 4.16 ± 0.14 V and the Chronaxy from 59.6 ± 1.22 μs to 75.0 ± 1.82 μs. Also, 1 blocked the generation of action potentials (IC50 0.36 ± 0.14 mM) of the intact dorsal root ganglion (DRG) neurons without altering the resting potential and input resistance. Carvacrol reduced the voltage-gated sodium current of dissociated DRG neurons (IC50 0.37 ± 0.05 mM). In this study it has been demonstrated that 1 blocks neuronal excitability by a direct inhibition of the vol...

  • Linalool blocks excitability in peripheral nerves and voltage-dependent Na+ current in dissociated dorsal root ganglia neurons.
    European Journal of Pharmacology, 2010
    Co-Authors: José Henrique Leal-cardoso, Humberto Cavalcante Joca, Kerly Shamyra Da Silva-alves, Francisco Walber Ferreira-da-silva, Tiago Dos Santos-nascimento, Flávio Henrique Pequeno De Macedo, Pedro Militão De Albuquerque-neto, Pedro Jorge Caldas Magalhães, Saad Lahlou, Jader Santos Cruz
    Abstract:

    Linalool is a terpene that occurs as a major constituent of essential oils of many plants of widespread distribution. It possesses several biological and pharmacological activities, including depressant effects on the central nervous system and olfactory receptors. The present study investigated whether linalool affects the excitability of peripheral components of the somatic sensory system. We used sciatic nerve and preparations of intact and dissociated neurons of dorsal root ganglion for extracellular, intracellular and patch-clamp recordings. Linalool concentration-dependently (0.3-2.0mM) and reversibly blocked the excitability of the sciatic nerve. It inhibited peak-to-peak amplitude of the compound action potential (IC(50) was 0.78+/-0.04 mM). At 0.8mM, it reversibly increased rheobase and Chronaxy (from 3.2+/-0.1 V and 52.4+/-4.1 micros to 4.2+/-0.3 V and 71.2+/-5.5 micros (n=5), respectively) and inhibited with greater pharmacological potency the amplitude of the compound action potential components corresponding to axons with slower velocity of conduction. In a similar concentration range (0.1-6mM), linalool concentration-dependently and reversibly blocked the generation of action potentials of intact dorsal root ganglion neurons without alteration of resting membrane potential and input resistance, and inhibited the voltage-gated Na(+) current of dissociated dorsal root ganglion neurons. In conclusion, we demonstrated that linalool acts on the somatic sensory system with local anesthetic properties, since it blocked the action potential by acting on voltage-dependent Na(+) channels. This finding is important in showing the potential usefulness of linalool as a pharmacotherapeutic agent.

  • Effects of estragole on the compound action potential of the rat sciatic nerve
    Brazilian Journal of Medical and Biological Research, 2004
    Co-Authors: José Henrique Leal-cardoso, B.g. Matos-brito, J.e.g. Lopes-junior, K.v. Viana-cardoso, A.b. Sampaio-freitas, R.o. Brasil, Andrelina Noronha Coelho-de-souza, A.a.c. Albuquerque
    Abstract:

    Estragole, a relatively nontoxic terpenoid ether, is an important constituent of many essential oils with widespread applications in folk medicine and aromatherapy and known to have potent local anesthetic activity. We investigated the effects of estragole on the compound action potential (CAP) of the rat sciatic nerve. The experiments were carried out on sciatic nerves dissected from Wistar rats. Nerves, mounted in a moist chamber, were stimulated at a frequency of 0.2 Hz, with electric pulses of 50-100-micros duration at 10-20 V, and evoked CAP were monitored on an oscilloscope and recorded on a computer. CAP control parameters were: peak-to-peak amplitude (PPA), 9.9 +/- 0.55 mV (N = 15), conduction velocity, 92.2 +/- 4.36 m/s (N = 15), Chronaxy, 45.6 +/- 3.74 micros (N = 5), and rheobase, 3.9 +/- 0.78 V (N = 5). Estragole induced a dose-dependent blockade of the CAP. At 0.6 mM, estragole had no demonstrable effect. At 2.0 and 6.0 mM estragole, PPA was significantly reduced at the end of 180-min exposure of the nerve to the drug to 85.6 +/- 3.96 and 13.04 +/- 1.80% of control, respectively. At 4.0 mM, estragole significantly altered PPA, conduction velocity, Chronaxy, and rheobase (P < or = 0.05, ANOVA; N = 5) to 49.3 +/- 6.21 and 77.7 +/- 3.84, 125.9 +/- 10.43 and 116.7 +/- 4.59%, of control, respectively. All of these effects developed slowly and were reversible upon a 300-min wash-out. The data show that estragole dose-dependently blocks nerve excitability.