Changes in [Ca2+]i induced by several glucose transport-enhancing stimuli in rat epitrochlearis muscle

2003 ◽  
Vol 94 (5) ◽  
pp. 1813-1820 ◽  
Author(s):  
Shin Terada ◽  
Isao Muraoka ◽  
Izumi Tabata

The purpose of the present investigation was to establish a method for estimating intracellular Ca2+ concentrations ([Ca2+]i) in isolated rat epitrochlearis muscles. Epitrochlearis muscles excised from 4-wk-old male Sprague-Dawley rats were loaded with a fluorescent Ca2+indicator, fura 2-AM, for 60–90 min at 35°C in oxygenated Krebs-Henseleit buffer. After fura 2 loading and subsequent 20-min incubation, the intensities of 500-nm fluorescence, induced by 340- and 380-nm excitation lights (Ftotal340 and Ftotal380), were measured. The fluorescences specific to fura-2 (Ffura 2340 and Ffura 2380) were calculated by subtracting the non-fura 2-specific component from Ftotal340 and Ftotal380, respectively. The ratio of Ffura 2340 to Ffura 2380 was calculated as R, and the change in the ratio from the baseline value (ΔR) was used as an index of the change in [Ca2+]i. In resting muscle, ΔR was stable for 60 min. Incubation for 20 min with caffeine (3–10 mM) significantly increased ΔR in a concentration-dependent manner. Incubation with hypoxic Krebs-Henseleit buffer for 10–60 min significantly elevated ΔR, depending on the duration of the incubation. Incubation with 50 μM N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide for 20 min significantly elevated ΔR ( P < 0.05). No significant increases in ΔR were observed during incubation for 20 min with 2 mM 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside or with 2 mU/ml insulin. These results demonstrated that, by using the fura 2-AM fluorescence method, the changes in [Ca2+]i can be monitored in the rat epitrochlearis muscle and suggest that the method can be utilized to observe quantitative information regarding [Ca2+]i that may be involved in contraction- and hypoxia-stimulated glucose transport activity in skeletal muscle.

Molecules ◽  
2020 ◽  
Vol 25 (4) ◽  
pp. 892 ◽  
Author(s):  
Zetty Zulikha Hafiz ◽  
Muhammad ‘Afif Mohd Amin ◽  
Richard Muhammad Johari James ◽  
Lay Kek Teh ◽  
Mohd Zaki Salleh ◽  
...  

Centella asiatica (C. asiatica) is one of the medicinal plants that has been reported to exert comprehensive neuroprotection in vitro and in vivo. In view of this, the present study was performed to investigate the effect of ethanolic extract of C. asiatica, designated as raw-extract of C. asiatica (RECA) in reducing the acetylcholinesterase (AChE), inflammations, and oxidative stress activities via both in vitro (SH-SY5Y and RAW 264.7 cells) and in vivo (Sprague Dawley rats). Quantitative high-performance liquid chromatography analysis reveals that RECA contains a significantly high proportion of glycosides than the aglycones with madecassoside as the highest component, followed by asiaticoside. Treatment of SH-SY5Y cells with RECA significantly reduced the AChE activity in a concentration-dependent manner with an IC50 value of 31.09 ± 10.07 µg/mL. Furthermore, the anti-inflammatory and antioxidant effects of RECA were evaluated by lipopolysaccharides (LPS)-stimulated RAW 264.7 cells. Our results elucidated that treatment with RECA significantly suppressed the level of pro-inflammatory cytokine/mediators and oxidative stress released in a concentration-dependent manner. Interestingly, these patterns of inhibition were consistent as observed in the LPS-induced neuroinflammation Sprague Dawley rats’ model. The highest concentration used in the two models presented the most significant results. Herein, our findings strongly suggest that RECA may offer therapeutic potential for the treatment of Alzheimer’s disease through inhibiting the AChE, inflammation, and oxidative stress activities.


2020 ◽  
Vol 15 (4) ◽  
pp. 451-458
Author(s):  
Dong Joon Kim ◽  
Young Joon Ki ◽  
Bo Hyun Jang ◽  
Seongcheol Kim ◽  
Sang Hun Kim ◽  
...  

Background: Recently, there have been some trials to use dexmedetomidine in the obstetric field but concerns regarding the drug include changes in uterine contractions after labor. We aimed to evaluate the effects of dexmedetomidine on the myometrial contractions of pregnant rats.Methods: In a pilot study, the contraction of the myometrial strips of pregnant Sprague-Dawley rats in an organ bath with oxytocin at 1 mU/ml was assessed by adding dexmedetomidine from 10-6 to 10-2 M accumulatively every 20 min, and active tension and the number of contractions were evaluated. Then, changes in myometrial contractions were evaluated from high doses of dexmedetomidine (1.0 × 10−4 to 1.2 × 10−3 M). The effective concentrations (EC) for changes in uterine contractions were calculated using a probit model.Results: Active tension and the number of contractions were significantly decreased at 10-3 M and 10-4 M dexmedetomidine, respectively (P < 0.05). A complete loss of contractions was seen at 10-2 M. Dexmedetomidine (1.0 × 10−4 to 1.2 × 10−3 M) decreased active tension and the number of contractions in a concentration-dependent manner. The EC95 of dexmedetomidine for inhibiting active tension and the number of contractions was 5.16 × 10-2 M and 2.55 × 10-5 M, respectively.Conclusions: Active tension of the myometrium showed a significant decrease at concentrations of dexmedetomidine higher than 10-3 M. Thus, clinical concentrations of dexmedetomidine may inhibit uterine contractions. Further research is needed for the safe use of dexmedetomidine in the obstetrics field.


1998 ◽  
Vol 275 (4) ◽  
pp. G862-G867 ◽  
Author(s):  
Chantal A. Rivera ◽  
Michael D. Wheeler ◽  
Nobuyuki Enomoto ◽  
Ronald G. Thurman

This study investigated whether dietary choline can prevent endotoxin shock. Female Sprague-Dawley rats fed chow or chow plus choline chloride (0.025–0.4%) for 3 days were given lipopolysaccharide (LPS) via the tail vein. Eighty-three percent and 56% of chow-fed rats survived after 2.5 or 5.0 mg/kg LPS, respectively. Choline increased survival in a dose-dependent manner, with maximal effects observed at 0.4%; this dose of choline prevented mortality completely after 2.5 or 5 mg/kg LPS. Choline also improved the microscopic appearance of the lungs and blunted increases in serum aspartate aminotransferase levels. Intracellular Ca2+ was monitored in liver and lung macrophages during LPS exposure. Ca2+ increases in macrophages from choline-fed rats were blunted by 40–60% compared with chow-fed controls. Feeding choline also blunted tumor necrosis factor-α production. Feeding glycine, which prevents macrophage activation via a chloride channel, in addition to choline was even more effective than feeding choline alone, suggesting that glycine and choline act via distinct sites. These data are consistent with the hypothesis that choline diminishes endotoxin shock by preventing macrophage activation.


2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Edibe Karasu-Minareci ◽  
Irem Hicran Ozbudak ◽  
Gulay Ozbilim ◽  
Gulay Sadan

Phosphodiesterase type-5 (PDE-5) inhibitors are novel and important options for the treatment of pulmonary arterial hypertension (PAH). Therefore, we aimed to examine effects of vardenafil, a PDE-5 inhibitor, on the pulmonary arteries isolated from rats with monocrotaline- (MCT-) induced pulmonary hypertension. MCT (60 mg/kg) or its vehicle was administered by a single intraperitoneal injection to 6-week-old male Sprague Dawley rats. Rats were sacrificed 21 days after MCT injection, and the main pulmonary arteries were isolated and then mounted in 20 mL organ baths. Concentration-response curves for vardenafil (10−10–10−5 M) were constructed in phenylephrine- (Phe-) precontracted rings. PAH caused marked rightward shift in the curves to vardenafil whereas maximal responses were not affected. Inhibition of NO synthase (L-NAME, 10−4 M) or guanylyl cyclase (ODQ, 10−5 M) caused similar attenuation in responses evoked by vardenafil. Moreover, contraction responses induced by CaCl2(3×10−5–3×10−2 M) were significantly reduced in concentration-dependent manner by vardenafil. In conclusion, vardenafil induced pulmonary vasodilatation via inhibition of extracellular calcium entry in addition to NO-cGMP pathway activation. These results provide evidence that impaired arterial relaxation in PAH can be prevented by vardenafil. Thus, vardenafil represents a valuable therapeutic approach in PAH besides other PDE-5 inhibitors.


2000 ◽  
Vol 167 (3) ◽  
pp. 473-478 ◽  
Author(s):  
T Ebisawa ◽  
I Kondo ◽  
E Masaki ◽  
S Hori ◽  
M Kawamura

Capacitative Ca(2+) entry into bovine adrenocortical fasciculata cells was investigated by using the mobilization of intracellular Ca(2+) concentration ([Ca(2+)](i)) and Ca(2+)-induced steroidogenesis as the indicators. Bovine adrenocortical fasciculata cells on a glass coverslip were loaded with fura-2. The [Ca(2+)](i) mobilization was detected by a change of fura-2 fluorescence intensity. In the intracellular Ca(2+) store depleted cells, the addition of Ca(2+) to the incubation medium elicited a marked and sustained increase in [Ca(2+)](i). In the intracellular Ca(2+) store non-depleted cells, the addition of thapsigargin, an endoplasmic reticulum Ca(2+)-ATPase inhibitor, in the absence of extracellular Ca(2+), induced a slight and transient increase in [Ca(2+)](i), but an extensive and sustained increase in [Ca(2+)](i) was obtained by adding Ca(2+) to the incubation medium after the thapsigargin treatment. The sustained increase induced by thapsigargin was not inhibited by nifedipine, but was inhibited by Zn(2+) and Cd(2+) in a concentration-dependent manner. The effect of Zn(2+) was more potent than that of Cd(2+). Thapsigargin stimulated steroidogenesis in the presence of extracellular Ca(2+). The steroidogenic effect of thapsigargin was inhibited by Zn(2+) and Cd(2+) but not by nifedipine. These results suggest that there is, in bovine adrenocortical fasciculata cells, a steroidogenesis-linked Ca(2+) entry process other than that involving voltage-operated Ca(2+) channels and that the process might be capacitative Ca(2+) entry.


1998 ◽  
Vol 26 (4) ◽  
pp. 541-548
Author(s):  
Roger J. Price ◽  
Anthony B. Renwick ◽  
Paula T. Barton ◽  
J. Brian Houston ◽  
Brian G. Lake

This study investigated the effects of some experimental variables on the rate of xenobiotic metabolism in precision-cut rat liver slices. Liver slices of 123 ± 8μm (mean ± SEM of six slices), 165 ± 3μm, 238 ± 6μm and 515 ± 14μm thickness were prepared from male Sprague-Dawley rats, and incubated in RPMI 1640 medium in an atmosphere of 95% O2/5% CO2 by using a dynamic organ culture system. Liver slices of all thicknesses metabolised 10μM 7-ethoxycoumarin to total (free and conjugated) 7-hydroxycoumarin in a time-dependent manner. The rate of 7-ethoxycoumarin metabolism was greatest in 165μm thick slices and slowest in 515μm thick slices, being 2.74 ± 0.19pmol/minute/mg slice protein and 0.69 ± 0.07pmol/minute/mg slice protein, respectively. No marked effects on the rate of 7-ethoxycoumarin metabolism in liver slices were observed either by changing the medium to Earle's balanced salt solution (EBSS) or by changing the gas phase to 95% air/5% CO2. Moreover, the perfusion of rat livers with EBSS at 2–4°C, prior to preparation of tissue cores, did not enhance 7-ethoxycoumarin metabolism in rat liver slices. In this study, the optimal slice thickness was 175μm, with higher rates of 7-ethoxycoumarin metabolism being observed than with 250μm thick slices, which are often used for studies of xenobiotic metabolism. Variable results were obtained with slices of around 100–120μm thickness, which may be attributable to the ratio between intact hepatocytes and cells damaged by the slicing procedure in these very thin slices.


2001 ◽  
Vol 86 (5) ◽  
pp. 549-555 ◽  
Author(s):  
Hyun S. Park ◽  
Ji H. Ryu ◽  
Yeong L. Ha ◽  
Jung H. Y. Park

One of the objectives of the present study was to investigate whether 1 % conjugated linoleic acid (CLA) in the diet reduced tumour incidence in the colon of 1,2-dimethylhydrazine (DMH)-treated rats. Colon cancer was induced by injecting 6-week-old, male, Sprague–Dawley rats with 15 mg/kg DMH twice per week for 6 weeks. They were fed either 1 % CLA or a control diet ad libitum for 30 weeks. Dietary CLA significantly decreased colon tumour incidence (P<0·05). Our second objective was to investigate whether apoptosis in the colon mucosa of DMH-treated rats was affected by the amount of dietary CLA and whether the changes in apoptosis were related to those in fatty acid-responsive biomarkers. For this purpose, rats were killed after being fed a diet containing 0 %, 0·5 %, 1 % or 1·5 % CLA for 14 weeks. CLA was undetected in the mucosa of rats fed the 0 % CLA diet and increased to 5·9 mg/g phospholipid in rats fed the 0·5 % diet. The apoptotic index estimated by the terminal deoxynucleotidyl transferase-mediated dUTP nick and labelling technique was increased by 251 % and the 1,2-diacylglycerol content was decreased by 57 % in rats fed 0·5 % CLA. No further changes in these variables were observed when CLA in the diet was raised to 1·0 % or 1·5 %. However, dietary CLA decreased mucosal levels of prostaglandin E2, thromboxane B2 and arachidonic acid in a dose-dependent manner. The present data indicate that dietary CLA can inhibit DMH-induced colon carcinogenesis by mechanisms probably involving increased apoptosis.


1997 ◽  
Vol 87 (2) ◽  
pp. 354-360 ◽  
Author(s):  
Yumiko Ishizawa ◽  
Shuichiro Ohta ◽  
Hiroyuki Shimonaka ◽  
Shuji Dohi

Background Although hyper- and hypoglycemia induce neurophysiologic changes, there have been no reports on the effects of blood glucose changes on anesthetic requirements. This study examined the effects of hyper- and hypoglycemia on the minimum alveolar concentration (MAC) of halothane in rats. In addition, based on a previous finding that the level of brain acetylcholine was reduced during mild hypoglycemia, the authors examined the influence of physostigmine on MAC during hypoglycemia. Methods In Sprague-Dawley rats, anesthesia was induced and maintained with halothane in oxygen and air. The MAC was determined by observing the response to tail clamping and tested during mild hypoglycemia (blood glucose level, 60 mg/dl) and hyperglycemia (blood glucose level, 300 and 500 mg/dl) induced by insulin and glucose infusion, respectively (experiment 1). The effects of 0.3 and 1.0 mg/kg physostigmine given intraperitoneally on MAC were examined in rats with mild and severe hypoglycemia (blood glucose level, 60 and 30 mg/dl; experiment 2). Results In experiment 1, mild hypoglycemia significantly reduced the MAC of halothane (0.76 +/- 0.03%) compared with the control value (0.92 +/- 0.04%), but hyperglycemia did not change MAC. In experiment 2, mild and severe hypoglycemia reduced MAC of halothane in a degree-dependent manner. Physostigmine (1 mg/kg) had no effect on MAC regardless of blood glucose level, but 0.3 mg/kg reduced MAC. Conclusions Hypoglycemia reduced anesthetic requirements in a degree-dependent manner, whereas hyperglycemia had no effects. Although the mechanism of hypoglycemic MAC reduction needs further investigations, physostigmine studies suggest that this may not be related to inhibition of cholinergic transmission.


2021 ◽  
Vol 17 ◽  
Author(s):  
Gideon Ayeni ◽  
Mthokozisi Blessing Cedric Simelane ◽  
Shahidul Islam ◽  
Ofentse Jacob Pooe

Background: Medicinal plants together with their isolated bioactive compounds are known for their antioxidant properties which constitute therapeutic agents that are routinely employed in the treatment of liver diseases. Aims of the Study: The current study sought to explore the protective role of Warburgia salutaris and its isolated compound, iso-mukaadial acetate against carbon tetrachloride (CCl4)-induced hepatic injury. Methods: Thirty-five male Sprague Dawley rats were divided into seven groups of five animals each and injected with CCl4 to induce hepatic injury. Results: Treatment with the crude extract of W. salutaris and of iso-mukaadial acetate significantly reduced the levels of alkaline phosphatase, alanine and aspartate aminotransaminases, total bilirubin and malondialdehyde in a dose dependent manner, when compared to untreated groups. Liver histology revealed a reduction in hepatic necrosis and inflammation. Conclusion: The current investigation has demonstrated that W. salutaris extract and iso-mukaadial acetate could mitigate the acute liver injury inflicted by a hepatotoxic inducer in rats.


1994 ◽  
Vol 72 (4) ◽  
pp. 1973-1992 ◽  
Author(s):  
M. Tymianski ◽  
M. P. Charlton ◽  
P. L. Carlen ◽  
C. H. Tator

1. Cell-permeant Ca2+ chelators such as 1,2-bis-(2-amino-phenoxy)ethane- N,N,N',N'-tetraacetic acid acetoxymethyl ester (BAPTA-AM) protect neurons against excitotoxic and ischemic neuronal injury in vitro and in vivo. Here we provide the first steps toward characterizing the mechanisms by which these agents produce their neuroprotective effects. 2. Cultured mouse spinal neurons were simultaneously loaded with the Ca2+ indicator fura-2 and with one of three permeant chelators derived from the fast Ca2+ buffer BAPTA, or with ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid acetoxymethyl ester (EGTA-AM). Adding these chelators did not interfere with the fluorescence spectrum of fura-2 and had no effect on baseline [Ca2+]i. 3. The neurons were challenged with 250 microM L-glutamate for 50 min, producing a marked transient [Ca2+]i increase followed by a decay of [Ca2+]i to a lower “plateau.” About 80% of control neurons succumbed to this excitotoxic insult. Neurons that survived adjusted their plateau [Ca2+]i to lower levels than those that succumbed. 4. Neurons that were pretreated with permeant Ca2+ chelators became more resistant to these neurotoxic challenges. 5. We examined whether this reduction in glutamate neurotoxicity could be related to the given buffer's known Ca2+ affinity (Kd), its Ca2+ binding kinetics, and its ability to attenuate glutamate-induced [Ca2+]i increases. 6. Pretreatment of neurons with BAPTA analogues having Kds ranging from 100 to 3,600 microM 1) attenuated the amplitude and 2) lengthened the time constant describing the rise and decay of the glutamate-evoked [Ca2+]i transient. The magnitude of these effects paralleled the affinity of the chelator for Ca2+. 7. BAPTA-AM and its analogues dramatically attenuated the early neurotoxicity of glutamate, reducing cell deaths by up to 80%. However, in contrast with the graded effects of chelators having different Ca2+ affinities on Ca2+ transients, all BAPTA analogues were equally protective. These protective effects did not relate to the chelators' Ca2+ affinity within a Kd range of 100 nM (for BAPTA) to 3,600 nM (for 5,5'-dibromo BAPTA). 8. BAPTA-AM protected neurons in a concentration-dependent manner with 50% protection obtained with 10 microM, a concentration having no effect on the [Ca2+]i transient amplitude. 9. EGTA, a slow Ca2+ buffer with a similar Ca2+ affinity to BAPTA produced the same effects as BAPTA on [Ca2+]i transient kinetics. However, it was far less protective than BAPTA. 10. The time course of early glutamate neurotoxicity was altered by the BAPTA analogues, but not EGTA. BAPTA analogues caused a small increase in cell deaths in the first minutes of each experiment, followed by relative sparing from further neurodegeneration. 11. The ability of low Ca2+ affinity chelators such as 5,5'-dibromo BAPTA to protect neurons without markedly attenuating measured [Ca2+]i increases conflicts with the hypothesis that global elevations in [Ca2+]i are responsible for triggering neurotoxicity.(ABSTRACT TRUNCATED AT 400 WORDS)


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