Influx of Two Dipeptides, Glycylsarcosine and l-glutamyl-l-glutamic Acid, into hamster Jejunum in Vitro

1979 ◽  
Vol 56 (1) ◽  
pp. 15-23 ◽  
Author(s):  
D. M. Matthews ◽  
R. H. Gandy ◽  
E. Taylor ◽  
D. Burston
Keyword(s):  
Glutamic Acid ◽  
Brush Border ◽  
Transport Mechanism ◽  
Inhibitory Effect ◽  
The Other ◽  
Peptide Transport ◽  
High Concentration ◽  
Simple Diffusion ◽  
Diffusion Component

1. This paper reports an investigation of whether the dipeptides glycylsarcosine and l-glutamyl-l-glutamic acid share a single mediated transport mechanism into hamster jejunum, or whether one of these peptides is transported in part by a transport mechanism unavailable to the other. It describes the kinetics of influx of glycylsarcosine and of l-glutamyl-l-glutamic acid into rings of everted hamster jejunum in vitro, incubations being carried out at pH 5 in order to minimize brush-border and intra-medium hydrolysis of l-glutamyl-l-glutamic acid, so that peptide transport rather than a mixture of peptide transport and transport of free glutamic acid was studied. With glycylsarcosine, brush-border and intra-medium hydrolysis are negligibly small. 2. Estimates of the simple diffusion component in transport of each peptide were made by treating each of the substrates as a competitive inhibitor of its own mediated transport (assuming that mediated transport conforms to simple Michaelis-Menten kinetics), extrapolating the observed inhibitory effect over a range of concentrations to an infinitely high concentration of inhibitor, and estimating the transport component remaining at such a concentration. This component in transport would be expected to represent transport by simple diffusion, and this assumption was supported by the observation that for glycylsarcosine the uninhibitable component in transport was linearly proportional to substrate concentration; with l-glutamyl-l-glutamic acid the observations were too few to provide this demonstration. Estimates of apparent Kt and Vmax. for mediated transport of both peptides are given. Before correction for simple diffusion, linearizing plots were clearly biphasic for both peptides; after correction for simple diffusion, they became linear, providing no evidence for transport of either peptide by more than one mediated transport system, though not excluding the possibility of multiple systems. 3. Measurement of influx of [14C]Gly-Sar over a range of concentrations both alone and in the presence of a constant concentration of Glu-Glu showed that after correction for the non-mediated component in influx of Gly-Sar (simple diffusion), influx of this peptide conformed to Michaelis-Menten kinetics and the inhibitory effect of Glu-Glu on influx of Gly-Sar appeared to be competitive. The extent of inhibition corresponded well with that predicted from the Kt values of the two peptides. 4. Measurement of influx of [14C]Gly-Sar (1 mmol/l) in the presence of a range of concentrations of Glu-Glu, with extrapolation of the inhibitory effect of Glu-Glu to an infinitely high concentration of this peptide, showed that at such a concentration mediated influx of Gly-Sar was completely abolished, influx being reduced to the simple diffusion component in total influx of [14C]Gly-Sar. Measurement of influx of [14C]Glu-Glu (1 mmol/l) in the presence of a range of concentrations of Gly-Sar, with extrapolation of the inhibitory effect of Gly-Sar to an infinitely high concentration of this peptide, showed that at such a concentration mediated influx of Glu-Glu was completely abolished, influx being reduced to the simple diffusion component in total influx of [14C]Glu-Glu. 5. The results are compatible with the conclusion that Gly-Sar and Glu-Glu are taken up by the absorptive cells by a single mediated mechanism. They do not exclude the possibility that these peptides are taken up by multiple common mechanisms, but they do appear to exclude the possibility that at the substrate concentration used (1 mmol/l) there is appreciable uptake of one of the peptides by a system unavailable to the other.

Influx of Glycylsarcosine and l-Lysyl-l-Lysine into Hamster Jejunum in Vitro

1980 ◽  
Vol 58 (3) ◽  
pp. 221-225 ◽  
Author(s):  
E. Taylor ◽  
D. Burston ◽  
D. M. Matthews
Keyword(s):  
Amino Acid ◽  
Glutamic Acid ◽  
Amino Acid Uptake ◽  
The Other ◽  
Amino Acid Side Chain ◽  
Acid Uptake ◽  
High Concentration ◽  
Simple Diffusion ◽  
Wide Range

1. This paper reports an investigation of whether the dipeptides glycylsarcosine and l-lysyl-l-lysine share a single mediated transport mechanism into hamster jejunum, or whether one of these peptides is taken up in part by a mediated mechanism unavailable to the other. The investigation, using rings of everted jejunum in vitro, was carried out at pH 5 in order to reduce brush border and/or intramedium hydrolysis of lysyl-lysine. 2. The kinetics of uptake of each peptide was studied over a wide range of concentrations. Estimates of the simple diffusion component in uptake of each peptide were made by the method of self-inhibition of transport as previously described. After correction for simple diffusion, uptake of each peptide conformed to Michaelis-Menten kinetics, and values for Kt and Vmax. were obtained. 3. It was found that each peptide was capable, at infinitely high concentration, of complete inhibition of mediated uptake of the other. The inhibitory effect was competitive. We concluded that glycylsarcosine and lysyl-lysine were taken up by a common mediated mechanism (or possibly mechanisms), neither peptide being taken up by a mediated mechanism unavailable to the other. 4. A previous paper showed that l-glutamyl-l-glutamic acid and glycylsarcosine were taken up by a common mediated mechanism, and this paper shows that l-lysyl-l-lysine and glycylsarcosine are taken up by a common mediated mechanism. It is therefore postulated that the neutral dipeptide glycylsarcosine, the acidic dipeptide glutamyl-glutamic acid and the basic dipeptide lysyl-lysine all share a common mediated mechanism for uptake. This suggests that peptide uptake differs from amino acid uptake in that it is indifferent to the net charge on the amino acid side chain(s).

scholarly journals 2,4-EPIBRASSIONOLIDE ACTIVATES PRIMING RESISTANCE AGAINST RHIZOPUS STOLONIFER INFECTION IN PEACH FRUIT

2020 ◽  
Vol 49 (2) ◽  
pp. 135-143
Author(s):  
C.H. Li ◽  
M.Y. Du ◽  
K.T. Wang
Keyword(s):  
Fungal Infection ◽  
Inhibitory Effect ◽  
The Other ◽  
Antifungal Compounds ◽  
Rhizopus Stolonifer ◽  
Peach Fruit ◽  
Direct Inhibitory Effect ◽  
Potential Alternative ◽  
Direct Toxicity

This study was conducted to assess the effects of 2,4-epibrassionolide (EBR) on mold decay caused by Rhizopus stolonifer and its capability to activate biochemical defense reactions in postharvest peaches. The treatment of EBR at 5 μM possessed the optimum effectiveness on inhibiting the Rhizopus rot in peach fruit among all treatments. The EBR treatment significantly up-regulated the expression levels of a set of defense-related enzymes and PR genes that included PpCHI, PpGns1, PpPAL, PpNPR1, PpPR1 and PpPR4 as well as led to an enhancement for biosynthesis of phenolics and lignins in peaches during the incubation at 20 °C. Interestingly, the EBR-treated peaches exhibited more striking expressions of PR genes and accumulation of antifungal compounds upon inoculation with the pathogen, indicating a priming defense could be activated by EBR. On the other hand, 5 μM EBR exhibited direct toxicity on fungal proliferation of R. stolonifer in vitro. Thus, we concluded that 5 μM EBR inhibited the Rhizopus rot in peach fruit probably by a direct inhibitory effect on pathogen growth and an indirect induction of a priming resistance. These findings provided a potential alternative for control of fungal infection in peaches during the postharvest storage.

Inhibitory Effect Of High Concentration Of Oxygen On LPS-Induced Inflammation In Vivo And In Vitro

2011 ◽  
Author(s):  
MUNEHIRO YAMAGUCHI ◽  
AKIHIKO TANAKA ◽  
SHIN OHTA ◽  
TAKUYA YOKOE ◽  
YOSHITAKA YAMAMOTO ◽  
...  
Keyword(s):  
Inhibitory Effect ◽  
High Concentration

Kinetic studies on transport of PAH and other organic acids in isolated renal tubules

1965 ◽  
Vol 208 (2) ◽  
pp. 391-396 ◽  
Author(s):  
K. C. Huang ◽  
Dorothy S. T. Lin
Keyword(s):  
Organic Acids ◽  
Partition Coefficient ◽  
Transport Mechanism ◽  
Hippuric Acid ◽  
Kinetic Studies ◽  
Inhibitory Effect ◽  
Renal Tubules ◽  
High Concentration ◽  
Low Concentration ◽  
Tubular Transport

Studies were made on the uptake and washout of PAH and other organic acids in isolated renal tubules and cells at 25 C. The renal tubules accumulated PAH rapidly in the first 30-min period. Probenecid, its diethyl- and dimethyl analogues, hippuric acid, and 2,4-dinitrophenol inhibited the tubular transport of PAH competitively. A relationship between the inhibitory effect and the partition coefficient of the compound was observed; the higher the partition coefficient, the greater the inhibition. DNP was also accumulated in the isolated renal tubules. This accumulation was depressed by probenecid, indicating that DNP is probably transported by the same tubular transport mechanism for PAH and other organic acids. In washout experiments probenecid and DNP showed a biphasic action, namely, they stimulated the PAH washout in low concentration and inhibited it in high concentration However, hippuric acid, which has a low partition coefficient, demonstrated an augmentation of PAH washout even at a concentration of 2 x 10–2 m

Anionic and cationic exchange mechanisms in the skin of anurans, with special reference to Leptodactylidae in vivo

1971 ◽  
Vol 262 (842) ◽  
pp. 163-174 ◽  
Keyword(s):  
Transport Mechanism ◽  
Selective Inhibition ◽  
The Other ◽  
Sodium Absorption ◽  
Experimental Conditions ◽  
Net Flux ◽  
Cationic Exchange

In several species of anurans, the in vivo skin has been shown to absorb Na + and Cl - independently from dilute external solutions. That the mechanism for sodium absorption is different from that of chloride absroption is born out by the following: (1) Either of these ions is absorbed without an accompanying ion when this latter is impermeant. (2) From NaCl solutions there can be an unequal absorption of sodium and chloride. (3) A selective inhibition of the absorption of one of the ions can be produced experimentally, while the net flux of the other remains unchanged. In all these situations, the absorbed ion has to be exchanged against an endogenous ion of the same charge. In Calyptocephalella gayi , H + and HCO - 3 are exchanged against sodium and chloride respectively. A comparison of the relationships between H + excretion and Na + absorption in vivo skins and shortcircuited in vitro skins shows that in the latter no H + excretion occurs, only the Na + transport being maintained under these experimental conditions. From this, one must conclude that the active Na + transport is the motive factor of the transport mechanism. H + excretion by the in vivo skin plays the role of physiologically short-circuiting the Na + transport.

scholarly journals The Inhibitory Effect ofPrunella vulgarisL. on Aldose Reductase and Protein Glycation

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Hong Mei Li ◽  
Jin Kyu Kim ◽  
Jai Man Jang ◽  
Sang Oh Kwon ◽  
Cheng Bi Cui ◽  
...  
Keyword(s):  
Aldose Reductase ◽  
Inhibitory Effect ◽  
Protein Glycation ◽  
Prunella Vulgaris ◽  
Inhibitory Effects ◽  
Advanced Glycation ◽  
High Concentration ◽  
Potent Inhibition ◽  
Glycation End Products

To evaluate the aldose reductase (AR) enzyme inhibitory ability ofPrunella vulgarisL. extract, six compounds were isolated and tested for their effects. The components were subjected toin vitrobioassays to investigate their inhibitory assays using rat lens aldose reductase (rAR) and human recombinant AR (rhAR). Among them, caffeic acid ethylene ester showed the potent inhibition, with the IC50values of rAR and rhAR at3.2±0.55 μM and12.58±0.32 μM, respectively. In the kinetic analyses using Lineweaver-Burk plots of 1/velocity and 1/concentration of substrate, this compound showed noncompetitive inhibition against rhAR. Furthermore, it inhibited galactitol formation in a rat lens incubated with a high concentration of galactose. Also it has antioxidative as well as advanced glycation end products (AGEs) inhibitory effects. As a result, this compound could be offered as a leading compound for further study as a new natural products drug for diabetic complications.

scholarly journals CDK7 Inhibitor THZ1 Induces the Cell Apoptosis of B-Cell Acute Lymphocytic Leukemia by Perturbing Cellular Metabolism

2021 ◽  
Vol 11 ◽  
Author(s):  
Tuersunayi Abudureheman ◽  
Jing Xia ◽  
Ming-Hao Li ◽  
Hang Zhou ◽  
Wei-Wei Zheng ◽  
...  
Keyword(s):  
B Cell ◽  
Cell Apoptosis ◽  
Acute Lymphocytic Leukemia ◽  
Cellular Metabolism ◽  
Underlying Mechanism ◽  
Inhibitory Effect ◽  
Lymphocytic Leukemia ◽  
High Concentration ◽  
P53 Expression

B-cell acute lymphocytic leukemia (B-ALL) is a malignant blood cancer that develops in children and adults and leads to high mortality. THZ1, a covalent cyclin-dependent kinase 7 (CDK7) inhibitor, shows anti-tumor effects in various cancers by inhibiting cell proliferation and inducing apoptosis. However, whether THZ1 has an inhibitory effect on B-ALL cells and the underlying mechanism remains obscure. In this study, we showed that THZ1 arrested the cell cycle of B-ALL cells in vitro in a low concentration, while inducing the apoptosis of B-ALL cells in vitro in a high concentration by activating the apoptotic pathways. In addition, RNA-SEQ results revealed that THZ1 disrupted the cellular metabolic pathways of B-ALL cells. Moreover, THZ1 suppressed the cellular metabolism and blocked the production of cellular metabolic intermediates in B-ALL cells. Mechanistically, THZ1 inhibited the cellular metabolism of B-ALL by downregulating the expression of c-MYC-mediated metabolic enzymes. However, THZ1 treatment enhanced cell apoptosis in over-expressed c-MYC B-ALL cells, which was involved in the upregulation of p53 expression. Collectively, our data demonstrated that CDK7 inhibitor THZ1 induced the apoptosis of B-ALL cells by perturbing c-MYC-mediated cellular metabolism, thereby providing a novel treatment option for B-ALL.

Actions of NAD+ on renal brush border transport of phosphate in vivo and in vitro

1985 ◽  
Vol 249 (6) ◽  
pp. F948-F955 ◽  
Author(s):  
S. A. Kempson ◽  
S. T. Turner ◽  
A. N. Yusufi ◽  
T. P. Dousa
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Competitive Inhibition ◽  
Inhibitory Effect ◽  
Pi Transport ◽  
Renal Brush Border Membrane ◽  
Dependent Transport ◽  
Renal Brush Border

Previous studies showed that an increase in NAD+ content in renal cortex in vivo was accompanied by specific inhibition of Na+-dependent inorganic phosphate (Pi) transport across the renal brush border membrane (BBM). Further, in vitro addition of NAD+ to isolated renal BBM vesicles specifically inhibited Na+ gradient-dependent transport of Pi. The present study examined some aspects of the mechanism of this inhibition by NAD+ in vitro and in vivo. When NAD+ was increased in vivo by nicotinamide injection, the apparent Vmax was decreased, but the apparent Km was not different, indicating apparent noncompetitive inhibition. In the presence of 0.3 mM NAD+ added in vitro, the apparent Km for Na+-dependent Pi transport by BBM vesicles was increased, whereas the apparent Vmax was unchanged, indicating apparent competitive inhibition. These changes in apparent Km and apparent Vmax were identical when Pi uptake was measured either at 30-s or at 5-s (the initial rate) incubation times. Inhibition of Pi transport by BBM vesicles in vitro was due primarily to the action of intact added NAD+, although there may be some contribution by isotope dilution due to Pi released from NAD+ by enzymatic hydrolysis. Although in vitro inhibition of Pi transport by added NAD+ was reversed by washing the BBM, the inhibition due to increased NAD+ in vivo persisted after extensive washing of the isolated BBM. The specificity of the inhibitory effect of NAD+ in vivo was indicated by the finding that changes in renal cortical content of ATP or Pi, evoked by loading with glycerol or fructose, did not change BBM transport of Pi.(ABSTRACT TRUNCATED AT 250 WORDS)

A common pathway for sugar transport in hamster intestine

1961 ◽  
Vol 200 (1) ◽  
pp. 111-116 ◽  
Author(s):  
Charles R. Jorgensen ◽  
Bernard R. Landau ◽  
T. Hastings Wilson
Keyword(s):  
Small Intestine ◽  
Transport Mechanism ◽  
Sugar Transport ◽  
The Other ◽  
Common Pathway ◽  
In Vitro Method ◽  
Single Segment ◽  
Other Hand

The competition between different sugars for the transport mechanism of hamster small intestine was tested with an in vitro method which allowed the use of a single segment of intestine for both control and experimental periods. The transport of the test sugar d-galactose was inhibited by other sugars known to be actively absorbed by the intestine; namely, d-glucose, α-methyl-d-glucoside, i-deoxy-d-glucose, 6-deoxy-d-glucose and 3-o-methyl-d-glucose. On the other hand d-mannose and d-xylose, two sugars not actively transported, did not inhibit d-galactose absorption. In addition, sugars known to be actively absorbed produced an inhibition of transport of d-glucose and 6-deoxy-d-glucose when these were selected as test sugars. The results of these experiments are consistent with the view that all transported sugars compete for a common pathway in hamster intestine. Various hypotheses of sugar transport are discussed in light of the present data.

Inhibitory effects of calcium ionophore pretreatment of porcine oocytes on polyspermic fertilization

Zygote ◽  
2006 ◽  
Vol 14 (1) ◽  
pp. 17-22 ◽  
Author(s):  
T. Hayashi ◽  
H. Sato ◽  
H. Iwata ◽  
T. Kuwayama ◽  
Y. Monji
Keyword(s):  
Calcium Ionophore ◽  
Inhibitory Effect ◽  
Calcium Ionophore A23187 ◽  
The Other ◽  
Ionophore A23187 ◽  
Inhibitory Effects ◽  
High Concentration ◽  
Maturation Period ◽  
Low Concentration ◽  
Other Hand

The present study examined the inhibitory effects of various pretreatment concentrations (0–100 μM) of the calcium ionophore A23187 on polyspermic fertilization and then examined the effect of the maturation period and the time between calcium ionophore treatment and fertilization on the inhibitory effect of calcium ionophore on polyspermic fertilization. In experiment 1, a high concentration of calcium ionophore (100 μM) increased the rate of activated oocytes, but the rate of fertilization declined. On the other hand, when oocytes were treated with a low concentration of calcium ionophore (10 μM), monospermic fertilization was significantly increased (10 μM; 31.3%) (p < 0.05). In experiment 2, oocytes were cultured for various times (0, 0.5, 3, 6 h) after calcium ionophore treatment (10 μM) before fertilization. The highest rate of monospermic fertilization was detected in the oocytes cultured for 6 h after calcium ionophore treatment before fertilization. In experiments 3 and 4, we examined the effect of the maturation period (40 h or 44 h) on the rate of fertilization and blastulation of oocytes pretreated with calcium ionophore. The treatment of oocytes with calcium ionophore significantly decreased the rate of polyspermic fertilization regardless of the maturation period (44 h: with calcium ionophore 26.25% vs without 78.8%; 40 h: with calcium ionophore 37.5% vs without 77.5%); however, calcium ionophore treatment increased the rates of monospermic fertilization and blastulation of the oocytes matured for 44 h, but not those matured for 40 h. In conclusion, activation with a low concentration of calcium ionophore (10 μM) and a further 6 h of culture before fertilization improved the rate of monospermic fertilization and blastulation.

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