Succinylcholine Metabolite Succinic Acid Alters Steady State Activation in Muscle Sodium Channels

2000 ◽  
Vol 92 (5) ◽  
pp. 1385-1391 ◽  
Author(s):  
Gertrud Haeseler ◽  
Jacqueline Petzold ◽  
Hartmut Hecker ◽  
Axel Würz ◽  
Reinhard Dengler ◽  
...  
Keyword(s):  
Steady State ◽  
Succinic Acid ◽  
Sodium Channels ◽  
Animal Experiments ◽  
Cell Voltage ◽  
Hek293 Cells ◽  
Muscle Rigidity ◽  
Voltage Dependent

Background Animal experiments revealed that succinylcholine produced masseter muscle rigidity and activated myotonic discharges despite neuromuscular blockade with a nondepolarizing blocker. These results suggest that either succinylcholine or its metabolites might interfere directly with voltage-operated ion channels of the sarcolemma. The aim of this study was to examine effects of one product of succinylcholine hydrolysis, succinic acid, on voltage-gated muscle sodium (Na+) channels. Methods Alpha subunits of human muscle sodium channels were heterologously expressed in HEK293 cells. Activation of Na+ currents was examined applying standard whole-cell voltage-clamp protocols in the absence (control and washout) and presence of succinic acid in different concentrations (0.05-10 mm). Results Succinic acid shifted the midpoints of steady state activation plots in the direction of more negative test potentials, indicating that channels open during smaller depolarizations in the presence of the drug. The maximum amount of the negative shift in 10 mm succinic acid was -6.3 +/- 1.7 mV; the EC50 for this effect was 0.39 mm. In addition, succinic acid (10 mm) significantly enhanced maximum currents after depolarizations with respect to a series of control experiments. Conclusion Succinic acid facilitates voltage-dependent activation in muscle sodium channels in vitro. This might lead to muscle hyperexcitability in vivo.

A fast transient potassium current in thalamic relay neurons: kinetics of activation and inactivation

1991 ◽  
Vol 66 (4) ◽  
pp. 1304-1315 ◽  
Author(s):  
J. R. Huguenard ◽  
D. A. Coulter ◽  
D. A. Prince
Keyword(s):  
Steady State ◽  
Reversal Potential ◽  
Cell Voltage ◽  
Inactivation Kinetics ◽  
Voltage Dependent ◽  
Steady State Inactivation ◽  
K Current ◽  
K Currents ◽  
Relay Neurons

1. Whole-cell voltage-clamp techniques were used to record K+ currents in relay neurons (RNs) that had been acutely isolated from rat thalamic ventrobasal complex and maintained at 23 degrees C in vitro. Tetrodoxin (TTX; 0.5 microM) was used to block Na+ currents, and reduced extracellular levels of Ca2+ (1 mM) were used to minimize contributions from Ca2+ current (ICa). 2. In RNs, depolarizing commands activate K+ currents characterized by a substantial rapidly inactivating (time constant approximately 20 ms) component, the features of which correspond to those of the transient K+ current (IA) in other preparations, and by a smaller, more slowly activating K+ current, "IK". IA was reversibly blocked by 4-aminopyridine (4-AP, 5 mM), and the reversal potential varied with [K+]o as predicted by the Nernst equation. 3. IA was relatively insensitive to blockade by tetraethylammonium [TEA; 50%-inhibitory concentration (IC50) much much greater than 20 mM]; however, two components of IK were blocked with IC50S of 30 microM and 3 mM. Because 20 mM TEA blocked 90% of the sustained current while reducing IA by less than 10%, this concentration was routinely used in experiments in which IA was isolated and characterized. To further minimize contamination by other conductances, 4-AP was added to TEA-containing solutions and the 4-AP-sensitive current was obtained by subtraction. 4. Voltage-dependent steady-state inactivation of peak IA was described by a Boltzman function with a slope factor (k) of -6.5 and half-inactivation (V1/2) occurring at -75 mV. Activation of IA was characterized by a Boltzman curve with V1/2 = -35 mV and k = 10.8. 5. IA activation and inactivation kinetics were best fitted by the Hodgkin-Huxley m4h formalism. The rate of activation was voltage dependent, with tau m decreasing from 2.3 ms at -40 mV to 0.5 ms at +50 mV. Inactivation was relatively voltage independent and nonexponential. The rate of inactivation was described by two exponential decay processes with time constants (tau h1 and tau h2) of 20 and 60 ms. Both components were steady-state inactivated with similar voltage dependence. 6. Temperature increases within the range of 23-35 degrees C caused IA activation and inactivation rates to become faster, with temperature coefficient (Q10) values averaging 2.8. IA amplitude also increased as a function of temperature, albeit with a somewhat lower Q10 of 1.6. 7. Several voltage-dependent properties of IA closely resemble those of the transient inward Ca2+ current, IT. (ABSTRACT TRUNCATED AT 400 WORDS)

Effects of Probiotics in the Management of Infected Chronic Wounds: From Cell Culture to Human Studies

2020 ◽  
Vol 15 (3) ◽  
pp. 193-206
Author(s):  
Brognara Lorenzo ◽  
Salmaso Luca ◽  
Mazzotti Antonio ◽  
Di M. Alberto ◽  
Faldini Cesare ◽  
...  
Keyword(s):  
Chronic Wounds ◽  
Animal Experiments ◽  
Multidrug Resistant ◽  
Preliminary Evidence ◽  
Human Studies ◽  
In Vivo Studies ◽  
Resistant Bacteria ◽  
Keywords Probiotics

Background: Chronic wounds are commonly associated with polymicrobial biofilm infections. In the last years, the extensive use of antibiotics has generated several antibiotic-resistant variants. To overcome this issue, alternative natural treatments have been proposed, including the use of microorganisms like probiotics. The aim of this manuscript was to review current literature concerning the application of probiotics for the treatment of infected chronic wounds. Methods: Relevant articles were searched in the Medline database using PubMed and Scholar, using the keywords “probiotics” and “wound” and “injuries”, “probiotics” and “wound” and “ulcer”, “biofilm” and “probiotics” and “wound”, “biofilm” and “ulcer” and “probiotics”, “biofilm” and “ulcer” and “probiotics”, “probiotics” and “wound”. Results: The research initially included 253 articles. After removal of duplicate studies, and selection according to specific inclusion and exclusion criteria, 19 research articles were included and reviewed, accounting for 12 in vitro, 8 in vivo studies and 2 human studies (three articles dealing with animal experiments included also in vitro testing). Most of the published studies about the effects of probiotics for the treatment of infected chronic wounds reported a partial inhibition of microbial growth, biofilm formation and quorum sensing. Discussion: The application of probiotics represents an intriguing option in the treatment of infected chronic wounds with multidrug-resistant bacteria; however, current results are difficult to compare due to the heterogeneity in methodology, laboratory techniques, and applied clinical protocols. Lactobacillus plantarum currently represents the most studied strain, showing a positive application in burns compared to guideline treatments, and an additional mean in chronic wound infections. Conclusions: Although preliminary evidence supports the use of specific strains of probiotics in certain clinical settings such as infected chronic wounds, large, long-term clinical trials are still lacking, and further research is needed.

Inhibition of dihydropyridine-sensitive calcium entry in hypoxic relaxation of airway smooth muscle

1995 ◽  
Vol 268 (2) ◽  
pp. L201-L206 ◽  
Author(s):  
C. Vannier ◽  
T. L. Croxton ◽  
L. S. Farley ◽  
C. A. Hirshman
Keyword(s):  
Smooth Muscle ◽  
Airway Smooth Muscle ◽  
Muscle Tone ◽  
Bay K 8644 ◽  
O2 Concentration ◽  
Voltage Dependent ◽  
Progressive Hypoxia ◽  
Carbamyl Choline

Hypoxia dilates airways in vivo and reduces active tension of airway smooth muscle in vitro. To determine whether hypoxia impairs Ca2+ entry through voltage-dependent channels (VDC), we tested the ability of dihydropyridines to modulate hypoxia-induced relaxation of KCl- and carbamyl choline (carbachol)-contracted porcine bronchi. Carbachol- or KCl-contracted bronchial rings were exposed to progressive hypoxia in the presence or absence of 1 microM BAY K 8644 (an L-type-channel agonist). In separate experiments, rings were contracted with carbachol or KCl, treated with nifedipine (a VDC antagonist), and finally exposed to hypoxia. BAY K 8644 prevented hypoxia-induced relaxation in KCl-contracted bronchi. Nifedipine (10(-5) M) totally relaxed KCl- contracted bronchi. Carbachol-contracted bronchi were only partially relaxed by nifedipine but were completely relaxed when the O2 concentration of the gas was reduced from 95 to 0%. These data indicate that hypoxia can reduce airway smooth muscle tone by limiting entry of Ca2+ through a dihydropyridine-sensitive pathway, but that other mechanisms also contribute to hypoxia-induced relaxation of carbachol-contracted bronchi.

scholarly journals Perilla frutescens Leaf Extract and Fractions: Polyphenol Composition, Antioxidant, Enzymes (α-Glucosidase, Acetylcholinesterase, and Tyrosinase) Inhibitory, Anticancer, and Antidiabetic Activities

Foods ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 315
Author(s):  
Zhenxing Wang ◽  
Zongcai Tu ◽  
Xing Xie ◽  
Hao Cui ◽  
Kin Weng Kong ◽  
...  
Keyword(s):  
Ethyl Acetate ◽  
Animal Experiments ◽  
Ethyl Acetate Fraction ◽  
The Body ◽  
Total Phenolic ◽  
Antioxidant Power ◽  
Glycogen Accumulation ◽  
Inhibitory Ability

This study aims to evaluate the bioactive components, in vitro bioactivities, and in vivo hypoglycemic effect of P. frutescens leaf, which is a traditional medicine-food homology plant. P. frutescens methanol crude extract and its fractions (petroleum ether, chloroform, ethyl acetate, n-butanol fractions, and aqueous phase residue) were prepared by ultrasound-enzyme assisted extraction and liquid–liquid extraction. Among the samples, the ethyl acetate fraction possessed the high total phenolic (440.48 μg GAE/mg DE) and flavonoid content (455.22 μg RE/mg DE), the best antioxidant activity (the DPPH radical, ABTS radical, and superoxide anion scavenging activity, and ferric reducing antioxidant power were 1.71, 1.14, 2.40, 1.29, and 2.4 times higher than that of control Vc, respectively), the most powerful α-glucosidase inhibitory ability with the IC50 value of 190.03 μg/mL which was 2.2-folds higher than control acarbose, the strongest proliferative inhibitory ability against MCF-7 and HepG2 cell with the IC50 values of 37.92 and 13.43 μg/mL, which were considerable with control cisplatin, as well as certain inhibition abilities on acetylcholinesterase and tyrosinase. HPLC analysis showed that the luteolin, rosmarinic acid, rutin, and catechin were the dominant components of the ethyl acetate fraction. Animal experiments further demonstrated that the ethyl acetate fraction could significantly decrease the serum glucose level, food, and water intake of streptozotocin-induced diabetic SD rats, increase the body weight, modulate their serum levels of TC, TG, HDL-C, and LDL-C, improve the histopathology and glycogen accumulation in liver and intestinal tissue. Taken together, P. frutescens leaf exhibits excellent hypoglycemic activity in vitro and in vivo, and could be exploited as a source of natural antidiabetic agent.

scholarly journals Long noncoding RNA SNHG14 promotes hepatocellular carcinoma progression by regulating miR-876-5p/SSR2 axis

2021 ◽  
Vol 40 (1) ◽  
Author(s):  
Zhibin Liao ◽  
Hongwei Zhang ◽  
Chen Su ◽  
Furong Liu ◽  
Yachong Liu ◽  
...  
Keyword(s):  
Noncoding Rna ◽  
Animal Experiments ◽  
Luciferase Reporter ◽  
Western Blot Assay ◽  
Downstream Target ◽  
Protein Levels ◽  
Elevated Expression ◽  
Rna Immunoprecipitation

Abstract Background Aberrant expressions of long noncoding RNAs (lncRNAs) have been demonstrated to be related to the progress of HCC. The mechanisms that SNHG14 has participated in the development of HCC are obscure. Methods Quantitative real-time PCR (qRT-PCR) was used to measure the lncRNA, microRNA and mRNA expression level. Cell migration, invasion and proliferation ability were evaluated by transwell and CCK8 assays. The ceRNA regulatory mechanism of SNHG14 was evaluated by RNA immunoprecipitation (RIP) and dual luciferase reporter assay. Tumorigenesis mouse model was used to explore the roles of miR-876-5p in vivo. The protein levels of SSR2 were measured by western blot assay. Results In this study, we demonstrated that SNHG14 was highly expressed in HCC tissues, meanwhile, the elevated expression of SNHG14 predicted poor prognosis in patients with HCC. SNHG14 promoted proliferation and metastasis of HCC cells. We further revealed that SNHG14 functioned as a competing endogenous RNA (ceRNA) for miR-876-5p and that SSR2 was a downstream target of miR-876-5p in HCC. Transwell, CCK8 and animal experiments exhibited miR-876-5p inhibited HCC progression in vitro and in vivo. By conducting rescue experiments, we found the overexpression of SSR2 or knocking down the level of miR-876-5p could reverse the suppressive roles of SNHG14 depletion in HCC. Conclusion SNHG14 promotes HCC progress by acting as a sponge of miR-876-5p to regulate the expression of SSR2 in HCC.

scholarly journals In Vitro and In Vivo Biosafety Analysis of Resorbable Polyglycolic Acid-Polylactic Acid Block Copolymer Composites for Spinal Fixation

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 29
Author(s):  
Seung Kyun Yoon ◽  
Jin Ho Yang ◽  
Hyun Tae Lim ◽  
Young-Wook Chang ◽  
Muhammad Ayyoob ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Animal Experiments ◽  
Polymeric Materials ◽  
Polyglycolic Acid ◽  
Poly Lactic Acid ◽  
Skin Sensitization ◽  
Spinal Fixation ◽  
In Vivo Degradation

Herein, spinal fixation implants were constructed using degradable polymeric materials such as PGA–PLA block copolymers (poly(glycolic acid-b-lactic acid)). These materials were reinforced by blending with HA-g-PLA (hydroxyapatite-graft-poly lactic acid) and PGA fiber before being tested to confirm its biocompatibility via in vitro (MTT assay) and in vivo animal experiments (i.e., skin sensitization, intradermal intracutaneous reaction, and in vivo degradation tests). Every specimen exhibited suitable biocompatibility and biodegradability for use as resorbable spinal fixation materials.

scholarly journals Preclinical Testing of Radiopharmaceuticals for the Detection and Characterization of Osteomyelitis: Experiences from a Porcine Model

Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4221
Author(s):  
Aage Kristian Olsen Alstrup ◽  
Svend Borup Jensen ◽  
Ole Lerberg Nielsen ◽  
Lars Jødal ◽  
Pia Afzelius
Keyword(s):  
Animal Model ◽  
Animal Models ◽  
Porcine Model ◽  
Animal Experiments ◽  
Radioactive Tracers ◽  
The Individual ◽  
Selection Of

The development of new and better radioactive tracers capable of detecting and characterizing osteomyelitis is an ongoing process, mainly because available tracers lack selectivity towards osteomyelitis. An integrated part of developing new tracers is the performance of in vivo tests using appropriate animal models. The available animal models for osteomyelitis are also far from ideal. Therefore, developing improved animal osteomyelitis models is as important as developing new radioactive tracers. We recently published a review on radioactive tracers. In this review, we only present and discuss osteomyelitis models. Three ethical aspects (3R) are essential when exposing experimental animals to infections. Thus, we should perform experiments in vitro rather than in vivo (Replacement), use as few animals as possible (Reduction), and impose as little pain on the animal as possible (Refinement). The gain for humans should by far exceed the disadvantages for the individual experimental animal. To this end, the translational value of animal experiments is crucial. We therefore need a robust and well-characterized animal model to evaluate new osteomyelitis tracers to be sure that unpredicted variation in the animal model does not lead to a misinterpretation of the tracer behavior. In this review, we focus on how the development of radioactive tracers relies heavily on the selection of a reliable animal model, and we base the discussions on our own experience with a porcine model.

Studies of Metabolism Mediated Mutagenicity In Vitro

1990 ◽  
Vol 18 (1_part_1) ◽  
pp. 243-250
Author(s):  
Dag Jenssen ◽  
Lennart Romert
Keyword(s):  
Cell Lines ◽  
Biological Effects ◽  
Animal Experiments ◽  
Culture Technique ◽  
Organ Perfusion ◽  
Isolated Cells ◽  
Toxicological Effect ◽  
In Vitro Methods

To understand the cause of the biological effects of xenobiotic metabolism in mammals, investigators have traditionally performed animal experiments by comparing the results of biochemical methods, such as measurement of enzyme activity analysis of the metabolites produced, with the observed toxicological effect. This article deals with in vitro methods for genotoxicity combined with drug metabolising preparations at the organelle, cell or organ levels, as exemplified by microsome preparations, isolated cells/cell lines and organ perfusion systems, respectively. The advantage of some of these methods for studying metabolism-mediated mutagenicity is that the measured endpoint reflects not only the bioactivating phase I reactions, but also the detoxifying phase II reactions, and the transfer of the non-conjugated reactive metabolites to other cells and their ability to cause mutations in these cells. In vivo, all these events are important factors in the initiation of cancer. A mechanistic advantage of the methods for metabolism-mediated mutagenicity in vitro is that the relevance of the different steps in metabolism for the mutational events can seldom be investigated in an in vivo assay. Furthermore, human studies can easily be performed using the co-culture technique with isolated human cells or cell lines.

scholarly journals Identification of the Active Ingredient and Beneficial Effects of Vitex rotundifolia Fruits on Menopausal Symptoms in Ovariectomized Rats

Biomolecules ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1033
Author(s):  
Ji Hwan Lee ◽  
Sullim Lee ◽  
Quynh Nhu Nguyen ◽  
Hung Manh Phung ◽  
Myoung-Sook Shin ◽  
...  
Keyword(s):  
Weight Gain ◽  
Body Weight Gain ◽  
Animal Experiments ◽  
Ovariectomized Rats ◽  
Biological Functions ◽  
Menopausal Syndrome ◽  
Active Constituents ◽  
Mcf 7

Estrogen replacement therapy is a treatment to relieve the symptoms of menopause. Many studies suggest that natural bioactive ingredients from plants resemble estrogen in structure and biological functions and can relieve symptoms of menopause. The fruit of V. rotundifolia, called “Man HyungJa” in Korean, is a traditional medicine used to treat headache, migraine, eye pain, neuralgia, and premenstrual syndrome in Korea and China. The aim of the present study was to confirm that V. rotundifolia fruit extract (VFE) exerts biological functions similar to those of estrogen in menopausal syndrome. We investigated its in vitro effects on MCF-7 cells and in vivo estrogen-like effects on weight gain and uterine contraction in ovariectomized rats. Using the polar extract, the active constituents of VFE (artemetin, vitexicarpin, hesperidin, luteolin, vitexin, and vanillic acid) with estrogen-like activity were identified in MCF-7 cells. In animal experiments, the efficacy of VFE in ameliorating body weight gain was similar to that of estrogen, as evidenced from improvements in uterine atrophy. Vitexin and vitexicarpin are suggested as the active constituents of V. rotundifolia fruits.

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