Characteristics of accumulation of ephedrine in rabbit atria

1976 ◽  
Vol 54 (2) ◽  
pp. 93-100 ◽  
Author(s):  
D. S. Golko ◽  
D. M. Paton
Keyword(s):  
Concentration Gradient ◽  
Initial Rate ◽  
Passive Diffusion ◽  
Extraneuronal Uptake ◽  
Metabolic Inhibitors ◽  
High Concentrations ◽  
6 Hydroxydopamine ◽  
Rabbit Atria

The characteristics of uptake of (±)-[β-14C]ephedrine were studied in isolated rabbit atria. Ephedrine was rapidly accumulated against the concentration gradient. From 5 × 10−7 to 10−2 M, uptake occurred at a uniform initial rate. Uptake was slightly inhibited by high concentrations of ouabain, cocaine, desipramine, lidocaine and phenethylamines, and by a reduction in the external Na+ concentration. Uptake was not, however, reduced by omission of K+ from the medium, by metabolic inhibitors or by a variety of drugs known to inhibit the extraneuronal uptake and binding of noradrenaline. Pretreatment of animals with 6-hydroxydopamine very significantly reduced the uptake of (±)-[3H]metaraminol, but did not alter the uptake of ephedrine. It was concluded that the uptake of ephedrine in rabbit atria occurred predominantly in extraneuronal tissues possibly as a result of passive diffusion followed by binding.

scholarly journals Application of DNA Shuffling as a Tool for Hydrolase Activity Improvement of Pseudomonas Strain

2020 ◽  
Vol 11 (1) ◽  
pp. 7735-7745
Keyword(s):  
Protein Engineering ◽  
Protoplast Fusion ◽  
Concentration Gradient ◽  
First Generation ◽  
Human Life ◽  
Genome Shuffling ◽  
Dna Shuffling ◽  
High Concentration ◽  
Mutant Strains ◽  
High Concentrations

Biotechnology is considered one of the most influential technologies in various areas of human life, including health, economics, and the environment. Protein engineering is one of the major biotechnology tools in the field of modification and advancement of biocatalysts capabilities. Among the most effective protein engineering methods, in particular, to improve the industrial strain capabilities, is the shuffling genome method. This study aimed to follow knowledge and biocatalysts engineering techniques based on DNA shuffling methods. In the first step, two procedures were followed (DES method and compatibility according to the concentration gradient of Diazinon) to obtain mutant strains. Acquired mutant strains from both methods were resistant to high concentrations of poison up to 3000 mg/L. The activity of these strains also demonstrated their elevated activity compared to parent samples. The highest activity was related to four strains IR1.G1, IR1.D8, IR1.D4, and IR1.D5, which were 0.234 U/ml, 0.1 U/ml, 0.098 U/ml, and 0.066 U/ml, respectively. The improved strain was obtained via the concentration gradient of the diazinon method (IRL1.G1 strain) in comparison with IRL1.D8 strain (owning highest activity through DES method) possesses excessive activity in 3000 mg/L concentration of Diazinon. The evaluated results of first-generation genome shuffling of strains (the first round of protoplast fusion) also indicated that those shuffled strains with the ability to grow in the vicinity of the toxin (3000 mg/L concentration of Diazinon) showed better activity than obtained mutated strains by both methods (concentration gradient of the toxin and the DES method). In the final stage, the best results were related to IRL1.F2, IRL1.F3, and IRL1.F1 shuffled strains with 0.541 mg/L, 0.523 mg/L, and 0.509 mg/L, respectively. The highest activity belonged to the IRL1.F2 genome shuffled strain (first round of protoplast fusion). This strain could grow in a high concentration of toxin, and also, the activity was increased 30, 3.6, and 2.3 times in comparison with the parent strain (IRL1), IRL.D8 mutant, and IRL1.G1, respectively.

scholarly journals Elucidating the mechanism of cellular uptake of fullerene nanoparticles

2021 ◽  
Vol 27 (2) ◽  
pp. 200658-0
Author(s):  
Yeonjeong Ha ◽  
Xianzhe Wang ◽  
Howard M. Liljestrand ◽  
Jennifer A. Maynard ◽  
Lynn E. Katz
Keyword(s):  
Active Transport ◽  
Cellular Uptake ◽  
Lipid Membranes ◽  
Culture Media ◽  
Passive Diffusion ◽  
Engineered Nanoparticles ◽  
Metabolic Inhibitors ◽  
Representative Cell ◽  
Fullerene Concentration ◽  
Microtubule Transport

Understanding the molecular interactions between biological cells and engineered nanoparticles is a key to evaluating potential toxicities to humans and the environment. This study developed a method to determine the mechanisms by which fullerene aggregates are distributed into a representative cell line, human intestinal Caco-2 cells. First, we determined that the presence of fetal bovine serum (FBS) in the cell culture media changes the particle characteristics and inhibits particle adsorptions onto cell surfaces. Second, significantly lower amounts of fullerene were internalized at 4°C, a temperature at which active transport mechanisms are effectively impeded, than at 37°C. Third, metabolic inhibitors of active transport and a microtubule transport inhibitor decreased fullerene uptake at 37°C. Fourth, cellular uptake of fullerene increased with increasing fullerene concentration, suggesting that passive diffusion into lipid membranes contributed to uptake over the broad concentration range used in this study. Together, these results indicate fullerene transport into cells occurs via two mechanisms: passive diffusion across the lipid bilayer and active transport including microtubule involved endocytosis. The results also suggest that simple physical-chemical partitioning models do not fully describe fullerene uptake, and instead, active transport models are also required to estimate the cellular uptake and toxicity of fullerene.

Active transport of potassium by heart mitochondria

1960 ◽  
Vol 198 (4) ◽  
pp. 847-854 ◽  
Author(s):  
Frank Ulrich
Keyword(s):  
Methylene Blue ◽  
Active Transport ◽  
Creatine Phosphate ◽  
Rabbit Heart ◽  
Potassium Transport ◽  
Heart Mitochondria ◽  
Metabolic Inhibitors ◽  
Mitochondrial Suspension ◽  
High Concentrations ◽  
Potassium Gradient

Rabbit heart mitochondria contained potassium which could not be removed with four washings of isotonic sucrose or sodium chloride at 0–4°C. Aging, increasing concentrations of potassium, and a number of metabolic poisons either partially or completely inhibited the active transport of potassium into heart mitochondria when these particles were incubated for 15 minutes in air at 37.4° in a medium to which alpha-ketoglutarate and AMP or ATP had been added. Compounds uncoupling oxidative phosphorylation—such as arsenite, 2,4-dinitrophenol, l-thyroxine, calcium chloride, dicumarol, pentachlorophenol and methylene blue—inhibited potassium transport but usually only at relatively high concentrations (10–3 m). With the exception of p-chloromercuribenzoate, neither aging nor metabolic inhibitors prevented the extrusion of water by the mitochondria in the presence of alpha-ketoglutarate and AMP or ATP. Although addition of either ATP or substrate alone to the mitochondrial suspension resulted in a significant increase in the potassium gradient, the latter was much greater when both substrate and ATP (or ADP or AMP) were added together. ADP or AMP alone caused a very slight but probably not significant increase in the potassium gradient and creatine phosphate had no effect.

scholarly journals Uptake and metabolism of myo-inositol by L1210 leukaemia cells

1988 ◽  
Vol 254 (1) ◽  
pp. 95-100 ◽  
Author(s):  
J D Moyer ◽  
N Malinowski ◽  
E A Napier ◽  
J Strong
Keyword(s):  
Steady State ◽  
De Novo ◽  
Initial Rate ◽  
Geometric Isomer ◽  
Passive Diffusion ◽  
Concentration Addition ◽  
Free Medium ◽  
Extracellular Concentration ◽  
L1210 Cells ◽  
Uptake And Metabolism

The initial rate of uptake of [3H]myo-inositol by L1210 murine leukaemia cells is directly proportional to the extracellular concentration and unaffected by several analogues of myo-inositol even at millimolar concentrations. Scyllitol, a geometric isomer of myo-inositol, partially inhibited the uptake of myo-inositol (40% at 0.1 mM). A portion of the uptake of myo-inositol was not inhibited even at 5 mM-scyllitol. At steady-state the intracellular concentration of [3H]myo-inositol is directly proportional to the extracellular concentration. Addition of myo-inositol to medium does not enhance the growth of L1210 cells; these cells can maintain an extracellular concentration of 20 microM-myo-inositol even when grown in myo-inositol-free medium. Synthesis of myo-inositol from glucose by L1210 cells was demonstrated by use of [13C]glucose and m.s. L1210 cells maintain myo-inositol pools by a combination of synthesis de novo and uptake of exogenous myo-inositol by either passive diffusion or a low affinity carrier.

scholarly journals The Uptake of Divalent Manganese Ion by Mature Normal Human Red Blood Cells

1960 ◽  
Vol 44 (2) ◽  
pp. 301-314 ◽  
Author(s):  
Robert I. Weed ◽  
Aser Rothstein
Keyword(s):  
Red Cells ◽  
Metabolic Inhibitors ◽  
Entry And Exit ◽  
Permeability Constant ◽  
Manganese Ion ◽  
Human Red Blood Cells ◽  
Metabolic Substrates ◽  
Normal Human ◽  
High Concentrations ◽  
Mn Concentration

At physiological pH and concentrations of Mn++ in excess of 5 x 10-4 M, study of the Mn++ ion movement into human red cells is complicated by physicochemical alterations of the ion itself. At concentrations below 5 x 10x4 M, the rate of uptake bears a linear relationship to the Mn++ concentration. The permeability constant for inward movement of Mn++ is 2.87 ± 0.13 (S.E.) x 10-9 cm./sec. The rate is not influenced by the addition of metabolic substrates such as glucose or adenosine or the metabolic inhibitors iodoacetate or fluoride. Co++, Ca++, and Mg++ do not appear to compete with Mn++ for entry, but at high concentrations relative to Mn++, they reduce the rate of entry. Ca++ is far more effective than Co++ or Mg++ in this regard. The permeability constant for outward Mn++ movement is 1.38 ± 0.21 (S.E.) x 10-9 cm./sec., about half of that for entry. This slower rate of outward movement is consistent with the finding that 40 to 60 per cent of the Mn++ taken up by the red cells is non-ultrafilterable. Less than 5 to 10 per cent of the Mn++ appears to be bound to the stroma. It is concluded that entry and exit of Mn++ is a process of passive diffusion involving no carriers, transport, or metabolic linkage.

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 Amino acid transport by resealed ghosts from pigeon erythrocytes

1982 ◽  
Vol 202 (3) ◽  
pp. 613-621
Author(s):  
K P Wheeler
Keyword(s):  
Amino Acids ◽  
Concentration Gradient ◽  
Acid Transport ◽  
Ph Values ◽  
Intracellular Amino Acids ◽  
Net Flux ◽  
High Concentrations ◽  
Dependent Transport ◽  
Resealed Ghosts ◽  
Net Fluxes

Resealed ghosts from pigeon erythrocytes were shown to haemolyse during incubation in isotonic media with pH values greater than about 7 and high concentrations of Na+ inside the ghosts seemed to enhance this effect. At lower pH values the ghosts were stable but still highly permeable to Na+ and K+, and moderately permeable to sucrose. Under the latter conditions the ghosts transported amino acids in a way qualitatively but not quantitatively similar to intact erythrocytes. The Na+-dependent transport of serine and alanine by the ghosts consisted essentially of an exchange of extracellular for intracellular amino acids, with no significant net flux. In contrast, net fluxes of glycine in the direction of the Na+-concentration gradient across the ghost membrane were demonstrated. However, under one condition a small net influx of glycine occurred against the prevailing Na+-concentration gradient. Unlike Na+-dependent glycine uptake, the uptake of six other amino acids by intact pigeon erythrocytes was not influenced by the nature of the anion present. The significance of these findings in relation to previous work on the Na+-gradient hypothesis of membrane transport is discussed.

scholarly journals Characteristics of Ion Transport in Kidney Cortex of Mammalian Hibernators

1966 ◽  
Vol 49 (6) ◽  
pp. 1221-1239 ◽  
Author(s):  
J. S. WILLIS
Keyword(s):  
Low Temperature ◽  
Initial Rate ◽  
Ground Squirrels ◽  
Metabolic Inhibitors ◽  
Kidney Cortex ◽  
Cortex Slices ◽  
State Concentration ◽  
Kidney Cortex Slices ◽  
K Transport

Slices of kidney cortex of two species of hibernating mammals (hamsters and ground squirrels) have been leached of K, and their subsequent ability to reaccumulate K in vitro has been determined at temperatures between 38° and 0°C. At 5°C (body temperature of a hibernating mammal) uptake is appreciable in kidney cortex of both species. In the kidney cortex of hamsters, for example, the tissue K of slices incubated at 5°C reaches the same steady-state concentration after 2 hours that is observed in slices at 38°C after 20 minutes. At 0°C there is also a measurable uptake. This K transport is blocked by metabolic inhibitors and, in ground squirrel kidneys, by ouabain. In kidney cortex slices from guinea pigs net K accumulation is slight at 5°C and absent at 0°C. The initial rapid uptake of K at 38°C occurs at the same rate in kidney cortex slices of hamsters as in those of rabbits. Lowering the temperature of incubation decreases this initial rate of uptake in hamster kidney slices with a Q10 of 1.8 between 38° and 15° and of 5.7 between 15° and 0°C. In hamsters this uptake of K has been shown to require the outward extrusion of Na. Conversely, about half of the outward extrusion of Na requires K in the medium, while the remainder appears to be independent of K. The conclusions warranted are that kidney cells of hibernators possess an unusual ability to transport ions at low temperature, that this ability does not depend upon a more rapid rate at higher temperatures, and that the characteristics of transport at low temperature are qualitatively similar to those at 38°C in cells of nonhibernators.

scholarly journals The Mechanism of Foliar Zinc Absorption in Pistachio and Walnut

1999 ◽  
Vol 124 (3) ◽  
pp. 312-317 ◽  
Author(s):  
Qinglong Zhang ◽  
Patrick H. Brown
Keyword(s):  
Juglans Regia ◽  
Leaf Age ◽  
Absorption Capacity ◽  
Metabolic Inhibitors ◽  
Stable Isotope Labelling ◽  
Zn Uptake ◽  
Detached Leaves ◽  
Uptake Process ◽  
High Concentrations ◽  
Walnut Leaves

The characteristics and mechanisms of foliar Zn uptake and translocation in pistachio (Pistachio vera L.) and walnut (Juglans regia L.) were investigated using 68Zn labelling in both intact and detached leaves. Following washing, mature walnut and pistachio leaves retained 8% and 12% of the total Zn applied, respectively. About half of retained Zn (3.5% and 6.5% of total Zn respectively) was absorbed into the leaf and translocated outside the treated area. Leaf age affected the Zn absorption capacity of pistachio but not walnut. Immature pistachio leaves absorbed more Zn than mature leaves. The absorption of Zn by walnut leaves at high concentrations (7.5 to 15 mm Zn) was not significantly affected by the pH of the solution. In pistachio Zn absorption was greatest at pH 3.5 and declined as pH increased to 8.5. The uptake process was not affected by light or addition of metabolic inhibitors. Foliar leaf absorption was only slightly affected by changes in temperature with an average Q10 of 1.2 to 1.4. This study suggests that foliar Zn uptake is dominated by an ion exchange and/or diffusion process rather than an active one. This study also demonstrates the usefulness of stable isotope labelling in studies of foliar Zn absorption.

Chlorimuron Absorption by Excised Velvetleaf (Abutilon theophrasti) Roots

Weed Science ◽  
1989 ◽  
Vol 37 (1) ◽  
pp. 29-33 ◽  
Author(s):  
Ujjanagouda B. Nandihalli ◽  
Prasanta C. Bhowmik
Keyword(s):  
Temperature Coefficient ◽  
Ethyl Ester ◽  
Concentration Gradient ◽  
External Solution ◽  
Abutilon Theophrasti ◽  
Root Tissue ◽  
Metabolic Inhibitors ◽  
Free Solution ◽  
Anaerobic Conditions

Absorption of ethyl ester of chlorimuron by excised velvetleaf root tissue was investigated. Chlorimuron uptake increased rapidly, reaching a maximum after 2 h. After 4 h, however, a portion of the previously absorbed herbicide was lost to the external solution. The temperature coefficient (Q10) for chlorimuron absorption between 15 and 25 C was 1.9. The herbicide uptake was severely inhibited by metabolic inhibitors, DNP and KCN, and by anaerobic conditions (anoxia). Results of permeation experiments indicated that chlorimuron did not accumulate in the root tissue against a concentration gradient, and Ci/Coreached 1.0 after a 2-h permeation period. Chlorimuron efflux was continuous and after 2 h of washing the tissue in a herbicide-free solution, 90% of the previously absorbed herbicide was removed, suggesting that its accumulation in the tissue was reversible.

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