Stimulatory effect of lithium on glucose transport in rat adipocytes is not mediated by elevation of IP1

1998 ◽  
Vol 275 (2) ◽  
pp. E272-E277 ◽  
Author(s):  
Xiaoli Chen ◽  
Ellen G. McMahon ◽  
Eric A. Gulve
Keyword(s):  
Glucose Uptake ◽  
Glucose Transport ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Transport Activity ◽  
Concentration Dependent Manner ◽  
Inositol 1 ◽  
Rat Adipocytes ◽  
Increase Glucose Uptake ◽  
Stimulation Of

Lithium has been shown to increase glucose uptake in skeletal muscle and adipose tissues. The therapeutic effect of lithium on bipolar disease is thought to be mediated by its inhibitory effect on myo-inositol-1-monophosphatase (IMPase). We tested the hypothesis that the stimulatory effect of lithium on glucose uptake results from inhibition of IMPase and the resultant accumulation of inositol monophosphates (IP1) by comparing the effects of lithium and a selective IMPase inhibitor, L-690,488, on isolated rat adipocytes. Insulin produced a concentration-dependent stimulation of 2-deoxy-d-[14C]glucose (2-DG) transport (10 μU/ml caused half-maximal activation). Acute exposure to lithium stimulated basal glucose transport activity in a concentration-dependent manner, with a threefold stimulation at 30 mM lithium. Lithium also potentiated insulin-stimulated 2-DG transport. Lithium produced a concomitant increase in IP1 accumulation. In contrast, L-690,488 increased IP1 to levels comparable to those of lithium without stimulatory effects on 2-DG transport. These results demonstrate that stimulatory effects of lithium on glucose transport are not mediated by the inhibition of IMPase and subsequent accumulation of IP1 in rat adipocytes.

Stimulation of renin secretion by ethacrynic acid is independent of Na(+)-K(+)-2Cl- cotransport

1990 ◽  
Vol 259 (4) ◽  
pp. F539-F544 ◽  
Author(s):  
C. S. Park ◽  
P. S. Doh ◽  
R. E. Carraway ◽  
G. G. Chung ◽  
J. C. Fray ◽  
...  
Keyword(s):  
Loop Diuretic ◽  
Ethacrynic Acid ◽  
Inhibitory Effect ◽  
Renin Secretion ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Specific Membrane ◽  
Cortical Slices ◽  
Stimulation Of

This study investigated the cellular mechanism of stimulation of renin secretion by the loop diuretic ethacrynic acid (EA) in rabbit renal cortical slices. The diuretic rapidly stimulated renin secretion reversibly and in a concentration-dependent manner. The stimulation was independent of the presence of Na+, Cl-, Ca2+, or other loop diuretics (furosemide and bumetanide) in the incubation media, suggesting that the stimulation in vitro was not dependent on the inhibitory effect of the diuretic on Na(+)-K(+)-2Cl-cotransport. The findings do not support the macula densa hypothesis. The stimulation by the diuretic was prevented and reversed by thiols such as cysteine and dithiothreitol, which also prevented and reversed the stimulation of renin secretion by the nondiuretic sulfhydryl reagent P-chloromercuriphenyl-sulfonate (PCMPS). These results suggest that EA stimulates renin secretion in vitro via reversible chemical reactions with specific membrane sulfhydryl groups that may have no functional role in the Na(+)-K(+)-2Cl- cotransport.

scholarly journals Myostatin regulates glucose uptake in BeWo cells

2007 ◽  
Vol 293 (5) ◽  
pp. E1296-E1302 ◽  
Author(s):  
Nisha Antony ◽  
John J. Bass ◽  
Christopher D. McMahon ◽  
Murray D. Mitchell
Keyword(s):  
Glucose Uptake ◽  
Cell Lines ◽  
Transforming Growth Factor ◽  
Muscle Growth ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Bewo Cells ◽  
Placental Cells

Myostatin is a member of the transforming growth factor (TGF)-β superfamily, known for its ability to inhibit muscle growth. It can also regulate metabolism and glucose uptake in a number of tissues. To determine the mechanism of myostatin's effect on glucose uptake, we evaluated its actions using choriocarcinoma cell lines that are widely used as models for placental cells. Protein and mRNA were determined using immunoblotting and RT-PCR/PCR, respectively. Glucose uptake was assessed by uptake of radiolabeled deoxyglucose in vitro. All choriocarcinoma cell lines tested i.e., BeWo, JEG, and Jar, are used as models of placental cells, and all expressed myostatin protein and mRNA. Treatment of BeWo cells with myostatin resulted in inhibition of glucose uptake in a concentration-dependent manner ( P < 0.01). At all concentrations tested, follistatin, a functional inhibitor of myostatin, completely blocked the inhibitory effect of myostatin (40 nM) on glucose uptake by BeWo cells (0.4 nM, P < 0.05). Follistatin treatment alone also increased glucose uptake (0.4 and 4 nM, P < 0.001; 40 nM, P < 0.05). Because BeWo cells proliferated and greater cell densities were achieved, glucose uptake declined irrespective of treatment. Myostatin treatment of BeWo cells did not alter the levels of myostatin receptor, ActRII A/B proteins. The levels of glucose transport proteins also remained unaltered in BeWo cells with myostatin treatment. This study has shown that myostatin specifically inhibits glucose uptake into BeWo cells, suggesting that locally produced myostatin may control glucose metabolism within the placenta.

Osmotic stimulation of Na(+)-K(+)-Cl- cotransport in squid giant axon is [Cl-]i dependent

1990 ◽  
Vol 258 (4) ◽  
pp. C749-C753 ◽  
Author(s):  
G. E. Breitwieser ◽  
A. A. Altamirano ◽  
J. M. Russell
Keyword(s):  
Giant Axon ◽  
Dose Dependence ◽  
Squid Giant Axon ◽  
Dependent Manner ◽  
Transport Activity ◽  
Concentration Dependent Manner ◽  
Giant Axons ◽  
Stepwise Increase ◽  
Osmotic Stimulation ◽  
Stimulation Of

The effects of increasing extracellular osmolality on unidirectional Cl- fluxes through the Na(+)-K(+)-Cl- cotransporter were studied in internally dialyzed squid giant axons. Hyperosmotic seawater stimulated bumetanide-sensitive Cl-influx at 150 mM intracellular Cl- concentration ([Cl-]i), whereas Cl- efflux was unaffected under comparable ionic conditions. Stimulation of bumetanide-sensitive Cl- influx was proportional to the increase in extracellular osmolality. Bumetanide-sensitive Cl- influx began to increase after a latency of approximately 20 min after a stepwise increase of extracellular osmolality and continued to increase for at least 70 min. The increased bumetanide-sensitive Cl- influx measured after 65 min of exposure to hyperosmotic external fluid was a function of the intracellular Cl- concentration; stimulation by hyperosmotic external fluids was observed at physiological [Cl-]i levels (greater than 100 mM) but not at lower [Cl-]i levels. Under both normo- and hyperosmotic conditions, intracellular Cl- inhibited Na(+)-K(+)-Cl- cotransport influx in a concentration-dependent manner. However, in hyperosmotic seawater, the dose dependence of inhibition by intracellular Cl- was shifted to higher [Cl-]i values. Therefore, we conclude that hyperosmotic extracellular fluids stimulate influx via the Na(+)-K(+)-Cl- cotransport by resetting the relation between [Cl-]i and transport activity.

β-Hydroxybutyrate inhibits insulin-mediated glucose transport in mouse oxidative muscle

2010 ◽  
Vol 299 (3) ◽  
pp. E364-E373 ◽  
Author(s):  
Takashi Yamada ◽  
Shi-Jin Zhang ◽  
Håkan Westerblad ◽  
Abram Katz
Keyword(s):  
Protein Kinase ◽  
Insulin Receptor ◽  
Glucose Uptake ◽  
Glucose Transport ◽  
Insulin Action ◽  
Ketone Body ◽  
Ketone Bodies ◽  
Dependent Manner ◽  
Concentration Dependent Manner

Blood ketone body levels increase during starvation and untreated diabetes. Here we tested the hypothesis that ketone bodies directly inhibit insulin action in skeletal muscle. We investigated the effect of d,l-β-hydroxybutyrate (BOH; the major ketone body in vivo) on insulin-mediated glucose uptake (2-deoxyglucose) in isolated mouse soleus (oxidative) and extensor digitorum longus (EDL; glycolytic) muscle. BOH inhibited insulin-mediated glucose uptake in soleus (but not in EDL) muscle in a time- and concentration-dependent manner. Following 19.5 h of exposure to 5 mM BOH, insulin-mediated (20 mU/ml) glucose uptake was inhibited by ∼90% (substantial inhibition was also observed in 3- O-methylglucose transport). The inhibitory effect of BOH was reproduced with d- but not l-BOH. BOH did not significantly affect hypoxia- or AICAR-mediated (activates AMP-dependent protein kinase) glucose uptake. The BOH effect did not require the presence/utilization of glucose since it was also seen when glucose in the medium was substituted with pyruvate. To determine whether the BOH effect was mediated by oxidative stress, an exogenous antioxidant (1 mM tempol) was used; however, tempol did not reverse the BOH effect on insulin action. BOH did not alter the levels of total tissue GLUT4 protein or insulin-mediated tyrosine phosphorylation of the insulin receptor and insulin receptor substrate-1 but blocked insulin-mediated phosphorylation of protein kinase B by ∼50%. These data demonstrate that BOH inhibits insulin-mediated glucose transport in oxidative muscle by inhibiting insulin signaling. Thus ketone bodies may be potent diabetogenic agents in vivo.

scholarly journals β 3-adrenergic receptors are responsible for the adrenergic inhibition of insulin-stimulated glucose transport in rat adipocytes

1993 ◽  
Vol 296 (1) ◽  
pp. 99-105 ◽  
Author(s):  
C Carpéné ◽  
E Chalaux ◽  
M Lizarbe ◽  
A Estrada ◽  
C Mora ◽  
...  
Keyword(s):  
Glucose Transport ◽  
Rank Order ◽  
Inhibitory Effect ◽  
Albumin Concentration ◽  
Dependent Manner ◽  
Insulin Effect ◽  
Rat Adipocytes ◽  
Beta 2 ◽  
Definition Of ◽  
Brl 37344

The inhibition of insulin-stimulated glucose transport by isoprenaline, a mixed beta-adrenergic-receptor (AR) agonist, is well documented in rat adipocytes. Since it has been described that rat adipocytes possess not only beta 1- and beta 2- but also beta 3-ARs, the influence of various subtype-selective beta-AR agonists and antagonists on 2-deoxyglucose (2-DG) transport was assessed in order to characterize the beta-AR subtype involved in the adrenergic counter-regulation of the insulin effect. The stimulation of 2-DG transport by insulin was counteracted, in a dose-dependent manner, by all the beta-AR agonists tested, and the magnitude of the inhibition followed the rank order: BRL 37344 > isoprenaline = noradrenaline >> dobutamine = procaterol. The same rank order of potency was obtained for lipolysis activation. This is not in accordance with the pharmacological definition of a beta 1- or a beta 2-adrenergic effect, but agrees with the pharmacological pattern of a beta 3-adrenergic effect. The inhibitory effect of the beta 3-agonist BRL 37344 on insulin-stimulated 2-DG transport was not reversed by either the selective beta 1-antagonist ICI 89406 or the beta 2-antagonist ICI 118551. In addition, neither of these beta-antagonists was able to block the isoprenaline and noradrenaline effects, supporting major beta 3-adrenoceptor-subtype involvement in the adrenergic inhibition of insulin-stimulated 2-DG transport. Like isoprenaline, BRL 37344 inhibited (60% inhibition) insulin-stimulated glucose transport only when adenosine deaminase was present in the assay. Furthermore, the maximal inhibitory effects of isoprenaline and BRL 37344 were not additive, and were both dependent on albumin concentration in the incubation medium: they increased when the albumin concentration decreased in the medium from 3.5 to 1%. To conclude, the similarities between isoprenaline and BRL 37344 action on insulin-stimulated 2-DG transport, the poor efficacy of the beta 1-/beta 2-agonists and the lack of effect of selective beta 1- and beta 2-antagonists are compelling arguments to support the important role of beta 3-adrenoceptors in the adrenergic inhibition of glucose transport in rat adipocytes.

scholarly journals Inhibitory Effect of Lidocaine on Cultured Porcine Aortic Endothelial Cell-dependent Antiaggregation of Platelets

1995 ◽  
Vol 83 (2) ◽  
pp. 374-381. ◽  
Author(s):  
Toshiharu Az-ma ◽  
MD Hardian ◽  
Osafumi Yuge
Keyword(s):  
Endothelial Cells ◽  
Platelet Rich Plasma ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Aortic Endothelial Cells ◽  
Topical Lidocaine ◽  
Vascular Spasm ◽  
Stimulation Of ◽  
Aortic Endothelial

Background Vascular spasm is a well-known complication during vascular surgery. Topical lidocaine is frequently used to prevent this spasm. However, the effects of lidocaine on the endothelium-dependent antiaggregation are not clear. Methods The aggregation of platelet-rich plasma (PRP) obtained from healthy volunteers was measured by the turbidimetric technique at 37 degrees C. (1) Cultured porcine aortic endothelial cells were preincubated with lidocaine (3.7 microM to 37 mM), NG-methyl-L-arginine (300 microM), or indomethacin (10 microM) for 30 min. The preincubation medium was exchanged with a medium containing +/- 1 microM bradykinin for 1-min stimulation of endothelial cells. One hundred microliters of the supernatant was then added to PRP (750 micro1) just after stimulation of PRP with collagen (4 micrograms/ml). (2) Authentic nitric oxide (NO) or prostacyclin (PGI2) was applied to collagen-stimulated PRP with or without lidocaine (100 micrograms/ml). Results (1) The supernatant from endothelial cells without bradykinin stimulation showed "basal" antiaggregation (13.8 +/- 3.2%; n = 6). Bradykinin enhanced the antiaggregation (100 +/- 0%; n = 6). NG-methyl-L-arginine or indomethacin (antagonists of NO or PGI2) inhibited the bradykinin-evoked antiaggregation (10.3 +/- 2.1% and 13.6 +/- 3.7%, respectively; n = 6). Simultaneous preincubation of both agents completely blocked the effect (-4.2 +/- 2.8%; n = 6). Lidocaine failed to influence basal antiaggregation, but it inhibited bradykinin-stimulated antiaggregation in a concentration-dependent manner (concentration causing 50% inhibition = 108 +/- 41 microM; n = 6). (2) In contrast, lidocaine did not shift the 50% effective concentration of NO (control, 1.3 +/- 0.1 microM vs. lidocaine, 1.6 +/- 0.1 microM) or PGI2 (control, 405 +/- 54 nM vs. lidocaine, 257 +/- 41 nM) for antiaggregation. Conclusions Our results suggest that lidocaine has an inhibitory effect on antiaggregation derived from endothelial cells, caused by the inhibition of NO and PGI2 released from endothelial cells.

Polymyxin B inhibits stimulation of glucose transport in muscle by hypoxia or contractions

1989 ◽  
Vol 256 (5) ◽  
pp. E662-E667 ◽  
Author(s):  
E. J. Henriksen ◽  
M. D. Sleeper ◽  
J. R. Zierath ◽  
J. O. Holloszy
Keyword(s):  
Electrical Stimulation ◽  
Glucose Transport ◽  
Skeletal Muscles ◽  
Contractile Activity ◽  
Sugar Transport ◽  
Polymyxin B ◽  
Inhibitory Effect ◽  
Transport Activity ◽  
Anionic Phospholipids ◽  
Stimulation Of

Glucose transport can be stimulated via two separate pathways in muscle. One is activated by insulin, the other by contractile activity and hypoxia. Polymyxin B, a cationic antibiotic that displaces Ca2+ from anionic phospholipids, is reported to selectively inhibit the stimulation of glucose transport by insulin in muscle. A purpose of the present study was to determine whether the inhibition by polymyxin B is actually restricted to insulin. We found that polymyxin B (250 micrograms/ml) significantly inhibited the stimulation of glucose transport in rat skeletal muscles not only by insulin and vanadate but also by hypoxia, electrical stimulation, and K+. Polymyxin B also decreased the tension developed in response to electrical stimulation or K+. Although polymyxin B inhibited the increase in sugar transport activity induced by insulin and hypoxia, it had no inhibitory effect on sugar transport after it had been stimulated by these agents. These results show that the inhibitory effect of polymyxin B on the stimulation of glucose transport is not specific for insulin action. They suggest that polymyxin B inhibits a step that is common to the two pathways for stimulating glucose transport in skeletal muscle.

Effects of glucose and insulin on development of impaired insulin action in muscle

1992 ◽  
Vol 262 (4) ◽  
pp. E440-E446 ◽  
Author(s):  
B. F. Hansen ◽  
S. A. Hansen ◽  
T. Ploug ◽  
J. F. Bak ◽  
E. A. Richter
Keyword(s):  
Glucose Uptake ◽  
Glucose Transport ◽  
Glycogen Synthase ◽  
Membrane Vesicles ◽  
Insulin Binding ◽  
Inhibitory Effect ◽  
Muscle Membrane ◽  
Dependent Manner ◽  
Insulin Receptor Tyrosine Kinase ◽  
Insulin Responsiveness

Rat hindquarters were perfused for 2 h with either 0, 5, or 25 mM glucose in combination with either 0, 50, or 20,000 microU insulin/ml, whereupon responsiveness of glucose uptake to 20,000 microU insulin/ml and 25 mM glucose was measured. Perfusion with 25 mM glucose and 20,000 microU insulin/ml resulted in an initial glucose uptake of 43.6 +/- 3.9 mumol.g-1.h-1, which decreased to 18.7 +/- 1.6 mumol.g-1.h-1 after 2 h (P less than 0.001). Omission of glucose from the perfusate prevented the decrease in responsiveness, whereas 5 mM glucose caused a lesser decrease (to 28.3 +/- 2.2 mumol.g-1.h-1). At 0 and 50 microU insulin/ml the effects of glucose were present but were less pronounced. The decrease in insulin responsiveness of glucose uptake (55%) was accompanied by a lesser decrease (29%) in muscle glucose transport, whereas glucose transport in muscle membrane vesicles, muscle insulin binding, and insulin receptor tyrosine kinase activity were unchanged. Muscle glycogen synthase activity decreased (P less than 0.005) during perfusion with 25 mM glucose and 20,000 microU insulin/ml but did not decrease during perfusion with no glucose and 20,000 microU insulin/ml. It is concluded that insulin responsiveness of glucose uptake in muscle is decreased by exposure to glucose in a dose-dependent manner and the inhibitory effect of glucose is enhanced by simultaneous insulin exposure. The mechanism behind this insulin resistance could partly be explained by a decrease in muscle membrane glucose transport, possibly caused by changes in intracellular milieu.

scholarly journals Phorbol esters imitate in rat fat-cells the full effect of insulin on glucose-carrier translocation, but not on 3-O-methylglucose-transport activity

1988 ◽  
Vol 249 (3) ◽  
pp. 865-870 ◽  
Author(s):  
C Mühlbacher ◽  
E Karnieli ◽  
P Schaff ◽  
B Obermaier ◽  
J Mushack ◽  
...  
Keyword(s):  
Glucose Transport ◽  
Binding Sites ◽  
Plasma Membranes ◽  
Cytochalasin B ◽  
Phorbol Esters ◽  
Fat Cells ◽  
Transport Activity ◽  
Rat Adipocytes ◽  
Glucose Carrier ◽  
Stimulation Of

Tumour-promoting phorbol esters have insulin-like effects on glucose transport and lipogenesis in adipocytes and myocytes. It is believed that insulin activates the glucose-transport system through translocation of glucose transporters from subcellular membranes to the plasma membrane. The aim of the present study was to investigate if phorbol esters act through the same mechanism as insulin on glucose-transport activity of rat adipocytes. We compared the effects of the tumour-promoting phorbol ester tetradecanoylphorbol acetate (TPA) and of insulin on 3-O-methylglucose transport and on the distribution of D-glucose-inhibitable cytochalasin-B binding sites in isolated rat adipocytes. Insulin (100 mu units/ml) stimulated 3-O-methylglucose uptake 9-fold, whereas TPA (1 nM) stimulated the uptake only 3-fold (mean values of five experiments, given as percentage of equilibrium reached after 4 s: basal 7 +/- 1.3%, insulin 60 +/- 3.1%, TPA 22 +/- 2.3%). In contrast, both agents stimulated glucose-transporter translocation to the same extent [cytochalasin B-binding sites (pmol/mg of protein; n = 7): plasma membranes, basal 6.2 +/- 1.0, insulin 13.4 +/- 2.0, TPA 12.7 +/- 2.7; low-density membranes, basal 12.8 +/- 2.1, insulin 6.3 +/- 0.9, TPA 8.9 +/- 0.7; high-density membranes, 6.9 +/- 1.1; insulin 12.5 +/- 1.0, TPA 8.1 +/- 0.9]. We conclude from these data: (1) TPA stimulates glucose transport in fat-cells by stimulation of glucose-carrier translocation; (2) insulin and TPA stimulate the carrier translocation to the same extent, whereas the stimulation of glucose uptake is 3-fold higher with insulin, suggesting that the stimulatory effect of insulin on glucose-transport activity involves other mechanisms in addition to carrier translocation.

scholarly journals Brassinolide Enhances the Level of Brassinosteroids, Protein, Pigments, and Monosaccharides in Wolffia arrhiza Treated with Brassinazole

Plants ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1311
Author(s):  
Magdalena Chmur ◽  
Andrzej Bajguz
Keyword(s):  
Plant Growth ◽  
Growth And Development ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Plant Growth And Development ◽  
Concentration Dependent Manner ◽  
Spectrophotometric Methods ◽  
Synthetic Inhibitor ◽  
Wolffia Arrhiza ◽  
First Time

Brassinolide (BL) represents brassinosteroids (BRs)—a group of phytohormones that are essential for plant growth and development. Brassinazole (Brz) is as a synthetic inhibitor of BRs’ biosynthesis. In the present study, the responses of Wolffia arrhiza to the treatment with BL, Brz, and the combination of BL with Brz were analyzed. The analysis of BRs and Brz was performed using LC-MS/MS. The photosynthetic pigments (chlorophylls, carotenes, and xanthophylls) levels were determined using HPLC, but protein and monosaccharides level using spectrophotometric methods. The obtained results indicated that BL and Brz influence W. arrhiza cultures in a concentration-dependent manner. The most stimulatory effects on the growth, level of BRs (BL, 24-epibrassinolide, 28-homobrassinolide, 28-norbrassinolide, catasterone, castasterone, 24-epicastasterone, typhasterol, and 6-deoxytyphasterol), and the content of pigments, protein, and monosaccharides, were observed in plants treated with 0.1 µM BL. Whereas the application of 1 µM and 10 µM Brz caused a significant decrease in duckweed weight and level of targeted compounds. Application of BL caused the mitigation of the Brz inhibitory effect and enhanced the BR level in duckweed treated with Brz. The level of BRs was reported for the first time in duckweed treated with BL and/or Brz.

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