Characteristics of spermidine uptake by isolated rat enterocytes

1989 ◽  
Vol 256 (5) ◽  
pp. G905-G910 ◽  
Author(s):  
J. Kumagai ◽  
R. Jain ◽  
L. R. Johnson
Keyword(s):  
Temperature Dependent ◽  
New Synthesis ◽  
Low Concentrations ◽  
Carrier Mechanism ◽  
Electrical Gradient ◽  
High Concentrations ◽  
The One ◽  
Energy Dependent ◽  
Rat Enterocytes ◽  
Isolated Rat

Eukaryotic cells require polyamines for growth. The supply of polyamines to growing cells may be increased either by new synthesis or increased uptake. We have recently shown that putrescine uptake by isolated rat enterocytes is energy dependent, saturable, and ouabain insensitive. Although putrescine uptake was inhibited by putrescine and cadaverine, it was not inhibited by equal concentrations of spermine and spermidine. These data indicated that a carrier mechanism separate from that putrescine existed for spermidine and spermine. In the current study spermidine uptake by isolated enterocytes was saturable, temperature dependent, and inhibited by 1 mM KCN. Kinetic analysis resulted in a Km = 2.51 x 10(-6) M and a Vmax = 3.57 x 10(-12) mol.10(6) cells-1.15 min-1. Spermidine uptake was 70% inhibited by 1 mM ouabain. Replacement of sodium by choline, lithium, tetramethylammonium, or N-methyl-D-glucamine also inhibited spermidine uptake. Replacement of Na+ by mannitol or sucrose, however, depressed uptake but not significantly. Spermidine uptake was inhibited by 1 mM ouabain. Spermidine uptake was inhibited by relatively low concentrations of spermine and high concentrations of putrescine; while putrescine uptake was inhibited by relatively high concentrations of both spermine and spermidine. Kinetic data indicated that spermidine and spermine share a carrier that is distinct from the one mediating the uptake of putrescine. While spermidine uptake does not appear to depend on Na+ cotransport, it may be dependent on the electrical gradient established by the Na+-K+-ATPase.

A carrier-mediated system for transport of biotin in rat intestine in vitro

1987 ◽  
Vol 252 (1) ◽  
pp. G52-G55 ◽  
Author(s):  
H. M. Said ◽  
R. Redha
Keyword(s):  
Methyl Ester ◽  
Temperature Dependent ◽  
Rat Intestine ◽  
Simple Diffusion ◽  
Low Concentrations ◽  
Structural Analogues ◽  
High Concentrations ◽  
Biotin Molecule ◽  
Energy Dependent

Transport of biotin was examined in rat intestine using the everted sac technique. Transport of 0.1 microM biotin was linear with time for at least 30 min of incubation and occurred at a rate of 3.7 pmol X g initial tissue wet wt-1 X min-1. Transport of biotin was higher in the jejunum than the ileum and was minimum in the colon (85 +/- 6, 36 +/- 6, and 2.8 +/- 0.6 pmol X g initial tissue wet wt-1 X 25 min-1, respectively). In the jejunum, transport of biotin was saturable at low concentrations (Kt = 3.73, microM, Vmax = 3.11 nmol X g initial tissue wet wt-1 X 25 min-1) but linear at higher concentrations (greater than 10 microM). The transport of low concentrations of biotin was inhibited by structural analogues (desthiobiotin, biotin methyl ester, diaminobiotin, and biocytin), Na+ dependent, energy dependent, temperature dependent, and proceeded against a concentration gradient in the serosal compartment. No metabolic alteration occurs to the biotin molecule during transport. This study demonstrates that biotin transport in rat intestine occurs by a carrier-mediated process at low concentrations and by simple diffusion at high concentrations. Furthermore, the carrier-mediated process is Na+, energy, and temperature dependent.

Characteristics of putrescine uptake in isolated rat enterocytes

1988 ◽  
Vol 254 (1) ◽  
pp. G81-G86 ◽  
Author(s):  
J. Kumagai ◽  
L. R. Johnson
Keyword(s):  
Amino Acids ◽  
Cellular Uptake ◽  
Concentration Gradient ◽  
Eukaryotic Cells ◽  
Temperature Dependent ◽  
New Synthesis ◽  
Polyamine Uptake ◽  
Sodium Replacement ◽  
Rat Enterocytes ◽  
Isolated Rat

Polyamines are necessary for the growth of eukaryotic cells and are supplied either by new synthesis or cellular uptake. To our knowledge, no information is available on polyamine uptake by gastrointestinal cells. In the current study, isolated villous enterocytes from the rat accumulated putrescine to an eightfold concentration gradient. Uptake was temperature dependent, saturable, and inhibited by 1 mM KCN. Kinetic analysis showed a Km of 1.23 X 10(-5) M and a Vmax of 2.60 X 10(-10) mol.10(6) cells-1.15 min-1. Enterocytes from the distal one-fourth of the gut showed the highest rate of uptake. Putrescine uptake was inhibited by cadaverine and spermine but not by the amino acids asparagine, AIB, or leucine. Sodium replacement by choline, lithium, N-methyl-D-glucamine, or tetramethylammonium significantly inhibited uptake, but replacement of Na+ by sucrose or mannitol was without effect. The inhibition observed was believed to be due to the ability of the cations to interact in some way with the carrier. Neither ouabain nor digitoxigenin had any effect on uptake. These data indicate that putrescine is accumulated by villous enterocytes by a carrier-mediated process that does not appear to involve Na+ contransport.

Low concentrations of interleukin-1 stimulate and high concentrations inhibit insulin release from isolated rat islets of Langerhans

1986 ◽  
Vol 113 (4) ◽  
pp. 551-558 ◽  
Author(s):  
Giatgen A. Spinas ◽  
Thomas Mandrup-Poulsen ◽  
Jens Mølvig ◽  
Leif Bæk ◽  
Klaus Bendtzen ◽  
...  
Keyword(s):  
Insulin Release ◽  
Interleukin 1 ◽  
Insulin Biosynthesis ◽  
Rat Islets ◽  
Low Concentrations ◽  
Isolated Rat Islets ◽  
High Concentrations ◽  
Rat Islets Of Langerhans ◽  
Isolated Rat

Abstract. Isolated rat islets were incubated either with crude, affinity-purified or recombinant human interleukin-1 for 1 to 6 days. A significant (20–60%) increase of insulin release was observed at low concentrations of all three interleukin-1-containing preparations. In contrast, higher concentrations dose-dependently inhibited the insulin release. The increased insulin secretion occurred at concentrations below those necessary to augment the mitogen response to phytohaemagglutinin of murine thymocytes in vitro. These doses (0.05-0.5 U/ml) correspond to 0.2-2 ng of recombinant interleukin-1 per ml, equal to approximately 0.01-0.1 pmol/ml. In doses of 0.6-1.8 U/ml affinitypurified interleukin-1 significantly increased the islet insulin content per ng of DNA, indicating a stimulation of insulin-biosynthesis. The data support the concept that low concentrations of interleukin-1 may play a role in priming the physiological secretion of insulin.

Copper, nickel, and thallium uptake by the lichen Cladina rangiferina

1981 ◽  
Vol 59 (1) ◽  
pp. 91-100 ◽  
Author(s):  
M. A. S. Burton ◽  
P. LeSueur ◽  
K. J. Puckett
Keyword(s):  
Metal Uptake ◽  
Deionized Water ◽  
Metabolic Inhibitors ◽  
Temperature Dependent ◽  
Low Concentrations ◽  
Nickel Uptake ◽  
High Concentrations ◽  
Uptake Studies ◽  
Cladina Rangiferina ◽  
Very High

Metal uptake studies with Cladina rangiferina showed that the affinity for nickel was much lower than for copper or thallium. Nickel uptake was not decreased by the absence of light or oxygen or by pretreatment with metabolic inhibitors. Nickel uptake was not temperature dependent but was very dependent upon pH.Cation-exchange studies demonstrated that there was a stoichiometric exchange of Ni2+ for Sr2+, and Cu2+ for Sr2+. The exchange of Tl+ for Sr2+ was not stoichiometric, excess Tl+ was accumulated in relation to the Sr2+ released. The ratio of Sr2+:Tl+ exchange increased with increasing Tl+ availability from 1:9 (12.5 μmol Tl+ available/g of lichen) to 1:2 (500 μmol Tl+ available). Acid-treated lichen gave the expected exchange ratio of 1:2. Washing of the thalli with deionized water resulted in the continued loss of Tl+ from acid-treated and live C. rangiferina. Copper and nickel were not released in this manner.Increasing concentrations of copper and thallium produced a corresponding loss of potassium from the thallus. The potassium loss was initiated at low concentrations of copper and thallium whereas very high concentrations of manganese and nickel were required to bring about the same response.

scholarly journals Temperature and the regulation of enzyme activity in poikilotherms. Properties of rainbow-trout fructose diphosphatase

1969 ◽  
Vol 111 (3) ◽  
pp. 287-295 ◽  
Author(s):  
H. W. Behrisch ◽  
P. W. Hochachka
Keyword(s):  
Enzyme Activity ◽  
Rainbow Trout ◽  
Temperature Adaptation ◽  
Temperature Dependent ◽  
Ph Optimum ◽  
Physiological Temperature ◽  
Low Concentrations ◽  
High Concentrations ◽  
Regulation Of Enzyme Activity ◽  
Hill Plots

1. The properties of fructose diphosphatase from the liver of rainbow trout (Salmo gairdnerii) were examined over the physiological temperature range of the organism. 2. Saturation curves for substrate (fructose 1,6-diphosphate) and a cofactor (Mg2+) are sigmoidal, and Hill plots of the results suggest a minimum of two interacting fructose 1,6-diphosphate sites and two interacting Mg2+ sites per molecule of enzyme. 3. Mn2+-saturation curves are hyperbolic, and the Ka for Mn2+, which inhibits the enzyme at high concentrations, is 50–100-fold lower than the Ka for Mg2+. 4. Fructose diphosphatase is inhibited by low concentrations of AMP; this inhibition appears to be decreased and reversed by increasing the concentrations of Mg2+ and Mn2+. Higher concentrations of AMP are required to inhibit the trout fructose diphosphatase in the presence of Mn2+. 5. The affinities of fructose diphosphatase for fructose diphosphate and Mn2+ appear to be temperature-independent, whereas the affinities for Mg2+ and AMP are highly temperature-dependent. 6. The pH optimum of the enzyme depends on the concentrations of Mg2+ and Mn2+. In addition, pH determines the Ka for Mg2+; at high pH, Ka for Mg2+ is lowered. 7. The enzyme is inhibited by Ca2+ and Zn2+, and the inhibition is competitive with respect to both cations. 8. The possible roles of these ions and AMP in the modulation of fructose diphosphatase and gluconeogenic activity are discussed in relation to temperature adaptation.

The Influence of Cu2+ on the Antioxidant System of Juncus effuses under the Low Temperature

2011 ◽  
Vol 414 ◽  
pp. 328-334
Author(s):  
Qi Hong Zhu ◽  
Hong Xia Xia
Keyword(s):  
Low Temperature ◽  
Antioxidant System ◽  
Early Stage ◽  
Heavy Metal Stress ◽  
Experimental Results ◽  
Sod Activity ◽  
Low Concentrations ◽  
High Concentrations ◽  
The One ◽  
In The Beginning

The influence of Cu2+ with different concentrations on the growth condition as well as the antioxidant system of Juncus effuses under low temperature has been analyzed through employing the hydroponic culture in this paper. The experimental results have shown that the Cu2+ can inhibit the SOD activity of Juncus effuses under the low temperature in the early stage of experiment, but it can promote the SOD activity of plants in the later stages of experiment. At the same time, the promotion of 30mg·L-1 is stronger than the one of 60mg·L-1. In the beginning of the experiment, the Cu2+ does not significantly affect the POD activity of plants. However, it can greatly improve the POD activity in later experiment and the promotion of low concentrations is stronger than the one of high concentrations. During the experiment, the activity of CAT enzyme can be promoted by the Cu2+ with low concentrations. But the Cu2+ with high concentrations will inhibit it at first and then promote it. What’s more, the promotion of Cu2+ with high concentrations is more effective than the one of Cu2+ with low concentrations. The experimental results have shown that the Juncus effuses can enhance the ability of resisting the heavy metal stress as well as improve the stress resistance of plants through adjusting the activities of oxidizing enzyme under the low temperature.

scholarly journals Putrescine uptake by the cellular slime mould dictyostelium discoideum

1979 ◽  
Vol 180 (1) ◽  
pp. 119-127 ◽  
Author(s):  
R Turner ◽  
M J North ◽  
J M Harwood
Keyword(s):  
Dictyostelium Discoideum ◽  
Fluid Phase ◽  
Bivalent Metal ◽  
Rapid Exchange ◽  
Low Concentrations ◽  
Bivalent Metal Ions ◽  
Cellular Slime ◽  
Uptake Process ◽  
High Concentrations ◽  
Energy Dependent

1. Rapid labelling occurs when myxamoebae of Dictyostelium discoideum strain AX2 are incubated with [1,4-14C]putrescine. Labelling is energy-dependent. 2. The label enters a pool from which rapid exchange with extracellular putrescine does not occur, and labelling is believed to represent uptake into the cells. 3. The concentration-dependence of putrescine uptake indicates that a number of systems are involved, at least one of which is saturable, with a Km of 9.1 micro M-putrescine. At high putrescine concentrations the overall uptake process is non-saturable. 4. Significant metabolism of putrescine and loss of intracellular putrescine to the medium only occurred when cells were incubated with millimolar concentrations of extracellular putrescine. 5. Putrescine uptake was inhibited by diamines, polyamines, bivalent metal ions and omega-aminocarboxylic acids. 6. The ability to take up putrescine at low concentrations decreased during starvation of myxamoebae. 7. The results are interpreted in terms of a model for putrescine uptake involving adsorptive pinocytosis at low concentrations and fluid-phase pinocytosis at high concentrations.

Gliadin binding to rat and human enterocytes

1987 ◽  
Vol 72 (5) ◽  
pp. 593-598 ◽  
Author(s):  
J. Colyer ◽  
P. J. Kumar ◽  
N. M. Waldron ◽  
M. L. Clark ◽  
M. J. G. Farthing
Keyword(s):  
Specific Binding ◽  
Surface Membrane ◽  
Con A ◽  
Specific Manner ◽  
Gliadin Peptides ◽  
Normal Human ◽  
High Concentrations ◽  
Rat Enterocytes ◽  
Isolated Rat ◽  
Primary Interaction

1. Binding of 125I-crude gluten digest (Frazer's fraction III, FF-III) and 125I-concanavalin A (Con A) to isolated rat enterocytes and of 125I-FF-III to human enterocytes was investigated. 2. Specific binding of 125I-FF-III to rat enterocytes was observed but binding was not inhibited by any of a range of simple and complex saccharides, although casein and bovine serum albumin displaced FF-III at high concentrations. 3. Con A also bound to enterocytes in a specific manner and was inhibited by α-methyl-D-mannoside, confirming a lectin-mediated interaction. 4. 125I-FF-III exhibited quantitatively similar specific binding to both normal human and coeliac enterocytes. 5. The primary interaction of gliadin peptides with the enterocyte surface membrane is not lectin-mediated and unlikely to be of fundamental importance in the pathogenesis of coeliac disease.

scholarly journals DYNAMICS OF ACRIDINE ORANGE-CELL INTERACTION

1964 ◽  
Vol 21 (1) ◽  
pp. 49-62 ◽  
Author(s):  
Elliott Robbins ◽  
Philip I. Marcus ◽  
Nicholas K. Gonatas
Keyword(s):  
Acid Phosphatase ◽  
Acridine Orange ◽  
Tricarboxylic Acid Cycle ◽  
Cell Interaction ◽  
Tricarboxylic Acid ◽  
Low Concentrations ◽  
High Concentrations ◽  
Short Time ◽  
Energy Dependent ◽  
Myelin Figures

The brilliantly fluorescent cytoplasmic particles that accumulate in HeLa cells treated with acridine orange, previously referred to as acridine orange particles, are shown to represent acid phosphatase positive multivesicular bodies (MVB). Dynamic changes in the ultrastructure of these organelles may be induced by varying the concentration of extracellular dye and the length of exposure to the dye. Low concentrations of dye for long intervals of time lead to marked hypertrophy of the MVB and accumulation of myelin figures within them, the acid phosphatase activity being retained. High concentrations of dye for short time intervals lead initially to a diffuse distribution of dye through out the cytoplasm (cytoplasmic reddening) as viewed in the fluorescence microscope. When cells are stained in this way and incubated in a dye-free medium, the diffusely distributed dye is segregated into MVB within 1 hour. Ultrastructurally, these MVB show dilatation but no myelin figures. The process of dye segregation is energy dependent and will not occur in starved cells. This energy dependence and the occurrence of segregation via dilatation of the MVB rather than ultrastructural transformation, i.e. formation of new binding sites, suggests that the process involves an active transport mechanism. Of the various energy sources supplied to starved cells, only glucose, mannose, and pyruvate are fully effective in supporting dye segregation. Blockage of the tricarboxylic acid cycle with malonate inhibits the effects of pyruvate but not of glucose, demonstrating the efficacy of both the tricarboxylic acid and glycolytic cycles in supplying energy for the process.

Reperfusion-induced arrhythmias: mechanisms of protection by glucose and mannitol

1988 ◽  
Vol 254 (5) ◽  
pp. H862-H870 ◽  
Author(s):  
M. Bernier ◽  
D. J. Hearse
Keyword(s):  
Radical Scavenging ◽  
Experimental Period ◽  
Free Radical Scavenging ◽  
Metabolic Effects ◽  
Low Concentrations ◽  
Rat Hearts ◽  
High Concentrations ◽  
Radical Scavenging Properties ◽  
Isolated Rat ◽  
Antiarrhythmic Effects

Isolated rat hearts (n = 15/group) were subjected to regional ischemia (10 min) and reperfusion (3 min). Mannitol (5, 11, 25, 50, 55, 61, or 75 mM included in the perfusate throughout) reduced reperfusion-induced sustained ventricular fibrillation (VF) from its control incidence of 93% (14/15) to 80, 80, 40, 27, 47, 80, and 80%, respectively. Addition of glucose (11 mM) potentiated this effect, VF now fell to 87, 47, 33, 7, 7, 7, 13, and 13%, respectively. However, 11 mM glucose alone exerted no antiarrhythmic effects. When hearts (n = 15/group) were perfused with identical osmotic loads of mannitol plus glucose (11 + 50, 50 + 11, 61 + 0, or 0 + 61 mM, respectively), very different antiarrhythmic effects were observed. When given throughout the experimental period, glucose alone (0, 11, 25, 50 or 61 mM) had no effect on the incidence of VF (93, 87, 47, 53, and 20%, respectively), but when glucose was added 2 min before reperfusion, improved protection was observed (VF: 93, 87, 40, 27, and 13%, respectively). Our results suggest that the osmotic and free-radical scavenging properties of hexoses are relatively unimportant in relation to their antiarrhythmic effects. The metabolic effects are complex, suggesting that low concentrations of glucose may be beneficial, whereas high concentrations may be detrimental.

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