16 research outputs found
Pharmacovigilance-pharmacological investigations on sulfonylureas and glinides-induced atrophy in skeletal muscle
No full textAntiproliferative effects of neuroprotective drugs targeting big Ca2+-activated K+ (BK) channel in the undifferentiated neuroblastoma cells
No full textThe big Ca2+-activated K+ (BK) channel has a role in regulating cell viability and survival in a variety of cells. The effects of drugs targeting the BK channels in neuronal and smooth muscle tissues in the human SH-SY5Y cell and mouse Neuro2A undifferentiated neuroblastoma cells have never been investigated. The expression/activity of BK channel subunits and the effects of the BK channel openers: acetazolamide (ACTZ) (10-7 - 2 × 10-4 M), resveratrol (RESV) (10-7 - 2 × 10-4 M), dichlorphenamide (DCP) (10-12 - 2 × 10-4 M), bendroflumethiazide (BFT) (10-9 - 10-5 M) and riluzole (RIL) (10-6 - 10-4 M) were evaluated by real time-polymerase chain reaction (RT-PCR)/patch-clamp experiments in SH-SY5Y cells and Neuro2a. Cell proliferation was evaluated by cell-dehydrogenase activity (CCK8-assay), cell impedentiometric (Scepter-counter) and clonogenic assays. An elevated expression/activity of the hslo1-BK channel subunit was observed in the SH-SY5Y, while a low expression/activity of this subunit was found in the Neuro2a. Tetraethylammonium (TEA) (1 - 5 x 10-3) and iberiotoxin (IbTX) (10-9 - 6 × 10-7 M) caused a marked inhibition of the whole-cell K+-currents in SH-SY5Y. A mild inhibition of the K+-currents was found in Neuro2a with these compounds. The application of ACTZ, DCP, RESV and BFT to the patches failed to activate the K+-currents but rather reduced it. The rank order of efficacy of the drugs as K+-current inhibitors at +30 mV (Vm) was: TEA > RESV ≥ IbTX > DCP > ACTZ > BFT. RESV and IbTX irreversibly reduced the K+-currents and the cell number in the enzymatic, clonogenic and impedentiometric assays with RESV being more effective than IbTX. TEA reversibly reduced the K+-currents without affecting cell proliferation. Whereas, RIL potentiated the BK current and reduced cell-dehydrogenases activity with no changes in the cell morphology and number. The observed irreversible BK channel-blocking action exerted by RESV and IbTX can be associated with anti-proliferative effects in cells overexpressing hslo1-BK channel subunit. This can be an additional mechanism contributing to the cytotoxic action of RESV in SH-SY5Y cells
ATP-DEPENDENT EFFECTS OF CROMAKALIM AND OF NEW SYNTHESIZED BENZOXAZINE DERIVATIVES ON MUSCLE KATP CHANNEL.
No full textEvaluation of drug efficacy on muscular dystrophy by in vivo treatments in exercised mdx mouse
No full textEvaluation of drug efficacy on muscular dystrophy by in vivo treatments in exercised mdx mouse
No full textThe alteration of calcium homeostasis in adult dystrophic mdx muscle fibers is worsened by a chronic exercise in vivo
No full textChronic exercise in vivo aggravates dystrophy in mdx mice. Calcium homeostasis was evaluated ex vivo by micro-spectrofluorometry on tendon-to-tendon dissected extensor digitorum longus (EDL) muscle fibers. Resting cytosolic calcium ([Ca2+]i) and sarcolemmal permeability through Gd3+-sensitive mechanosensitive calcium (MsCa) channel were significantly higher in mdx vs. wild-type fibers. The exercise further enhanced [Ca2+]i in mdx fibers and increased sarcolemmal permeability by activating nifedipine-sensitive leak calcium channels. The two genotypes did not differ in caffeine sensitivity and in the excitation-calcium release (ECaR) coupling mechanism by K+ depolarization. The exercise produced a similar adaptation of activation curve of ECaR and of sensitivity to caffeine. However, the inactivation of ECaR of mdx fibers did not adapt to exercise. No fiber phenotype transition occurred in exercised muscle. We provide the first evidence that an in vivo exercise worsens the impaired calcium homeostasis of dystrophic fibers, supporting the role of enhanced calcium entrance in dystrophic progression. © 2004 Elsevier Inc. All rights reserved
Alteration of excitation-contraction coupling mechanism in extensor digitorum longus muscle fibres of dystrophic mdx mouse and potential efficacy of taurine
No full text1. No clear data is available about functional alterations in the calcium-dependent excitation-contraction (e-c) coupling mechanism of dystrophin-deficient muscle of mdx mice. 2. By means of the intracellular microelectrode point voltage clamp method, we measured the voltage threshold for contraction (mechanical threshold; MT) in intact extensor digitorum longus (EDL) muscle fibres of dystrophic mdx mouse of two different ages: 8-12 weeks, during the active regeneration of hind limb muscles, and 6-8 months, when regeneration is complete. 3. The EDL muscle fibres of 8-12-week-old wildtype animals had a more negative rheobase voltage (potential of equilibrium for contraction- and relaxation-related calcium movements) with respect to control mice of 6-8 months. However, at both ages, the EDL muscle fibres of mdx mice contracted at more negative potentials with respect to age-matched controls and had markedly slower time constants to reach the rheobase. 4. The in vitro application of 60 mM taurine, whose normally high intracellular muscle levels play a role in e-c coupling, was without effect on 6-8-month-old wildtype EDL muscle, while it significantly ameliorated the MT of mdx mouse. 5. HPLC determination of taurine content at 6-8 months showed a significant 140% rise of plasma taurine levels and a clear trend toward a decrease in amino acid levels in hind limb muscles, brain and heart, suggesting a tissue difficulty in retaining appropriate levels of the amino acid. 6. The data is consistent with a permanent alteration of e-c coupling in mdx EDL muscle fibres. The alteration could be related to the proposed increase in intracellular calcium, and can be ameliorated by taurine, suggesting a potential therapeutic role of the amino acid
Enhanced dystrophic progression in mdx mice by exercise and beneficial effects of taurine and insulin-like growth factor-1
No full textAbstract
A preclinical screening for prompt-to-use drugs that are safer than steroids and beneficial in Duchenne muscular dystrophy was performed. Compounds able to reduce calcium-induced degeneration (taurine or creatine 10% in chow) or to stimulate regeneration [insulin-like growth factor-1 (IGF-1); 50 or 500 microg/kg s.c.] were administered for 4 to 8 weeks to mdx mice undergoing chronic exercise on a treadmill, a protocol to worsen dystrophy progression. alpha-Methyl-prednisolone (PDN; 1 mg/kg) was used as positive control. The effects were evaluated in vivo on forelimb strength and in vitro electrophysiologically on the macroscopic chloride conductance (gCl), an index of degeneration-regeneration events in mdx muscles, and on the mechanical threshold, a calcium-sensitive index of excitation-contraction coupling. The exercise produced a significant weakness and an impairment of gCl, by further decreasing the already low value of degenerating diaphragm (DIA) and fully hampering the increase of gCl typical of regenerating extensor digitorum longus (EDL) mdx muscle. The already negative voltage threshold for contraction of mdx EDL was also slightly worsened. Taurine > creatine > IGF-1 counteracted the exercise-induced weakness. The amelioration of gCl was drug- and muscle-specific: taurine was effective in EDL, but not in DIA muscle; IGF-1 and PDN were fully restorative in both muscles, whereas creatine was ineffective. An acute effect of IGF-1 on gCl was observed in vitro in untreated, but not in IGF-1-treated exercised mdx muscles. Taurine > PDN > IGF-1, but not creatine, significantly ameliorated the negative threshold voltage values of the EDL fibers. The results predict a potential benefit of taurine and IGF-1 for treating human dystrophy
Taurine ameliorates in vitro and in vivo the electrical and contractile properties of skeletal muscle fibres of dystrophic mdx mouse
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