scholarly journals Kinetic analysis of insulin action on amino acid uptake by isolated chick embryo heart cells

1971 ◽  
Vol 122 (4) ◽  
pp. 409-414 ◽  
Author(s):  
G. G. Guidotti ◽  
A. F. Borghetti ◽  
Britta Lüneburg ◽  
G. C. Gazzola
Keyword(s):  
Carbon Dioxide ◽  
Amino Acids ◽  
Amino Acid ◽  
Chick Embryo ◽  
Transport Systems ◽  
Heart Cells ◽  
Acid Uptake ◽  
Maximal Velocity ◽  
Chick Embryo Heart ◽  
Embryo Heart

1. Isolated chick embryo heart cells were used to investigate the mode of action of insulin on the transport of three naturally occurring amino acids: l-proline, l-serine and glycine. Initial velocities of uptake were measured over a period of 5min with an 80-fold range of amino acid concentration. Corrections for amino acid diffusion, incorporation into protein and conversion into carbon dioxide were introduced. 2. The uptake processes approximated Michaelis–Menten kinetics within definite ranges of amino acid concentrations. A single transport system for proline and at least two transport systems for serine and glycine were detected. 3. The kinetic effects of insulin on transport systems for the amino acids tested were consistent with an acceleration of the maximal velocity of the process, without substantial changes in substrate concentration for half-maximal transport velocity. 4. These hormonal effects were not essentially altered by the corrections for amino acid incorporation into protein and conversion into carbon dioxide.

scholarly journals Amino acid uptake in the developing chick embryo heart. The effect of insulin on α-aminoisobutyric acid accumulation

1968 ◽  
Vol 107 (4) ◽  
pp. 565-574 ◽  
Author(s):  
G. G. Guidotti ◽  
A. F. Borghetti ◽  
G. Gaja ◽  
L. Lo Reti ◽  
G. Ragnotti ◽  
...  
Keyword(s):  
Amino Acid ◽  
Chick Embryo ◽  
Incubation Medium ◽  
Transport Processes ◽  
Acid Uptake ◽  
Maximal Velocity ◽  
Aminoisobutyric Acid ◽  
Acid Accumulation ◽  
Chick Embryo Heart ◽  
Embryo Heart

1. The uptake of 14C-labelled α-aminoisobutyric acid by 5-day-old chick embryo hearts was investigated in vitro, together with the effect of insulin thereon. 2. At equilibrium the distribution ratio of this amino acid analogue between intracellular and extracellular water attained values greater than unity. Insulin enhanced the rate of α-aminoisobutyric acid accumulation and increased the value of its final concentration in the cell water. 3. The rate of α-aminoisobutyric acid accumulation and the effect of insulin on it were independent of the presence of glucose in the incubation medium. Bovine and chicken insulin were equally effective, and the action of the hormone was specifically prevented by an anti-insulin serum but not by puromycin. 4. A linear relationship was observed between the intracellular accumulation of the analogue and the logarithm of the insulin concentration in the range 50μunits–100m-units/ml. of incubation medium. 5. Evidence was obtained for the occurrence of two different transport processes for α-aminoisobutyric acid in the chick embryo heart: one subject to saturation and one that was not saturated by reasonable concentrations of the analogue. Insulin increased the effectiveness of the saturable component, increasing the maximal velocity of transport without altering the concentration for half-maximal velocity of transport, and decreased the contribution of the non-saturable component.

FURTHER STUDIES ON THE DUAL REQUIREMENT FOR PHENYLALANINE AND TYROSINE IN TISSUE CULTURE

1961 ◽  
Vol 39 (5) ◽  
pp. 925-932 ◽  
Author(s):  
Helen J. Morton ◽  
Joseph F. Morgan
Keyword(s):  
Amino Acids ◽  
Tissue Culture ◽  
Chick Embryo ◽  
Heart Cells ◽  
Present System ◽  
Chick Heart ◽  
High Concentrations ◽  
Chick Embryo Heart ◽  
Embryo Heart ◽  
Related Compounds

Seventeen structurally related compounds were tested for their ability to substitute for phenylalanine or tyrosine in the nutrition of chick embryo heart fragments. DL-Alanyl-DL-phenylalanine replaced phenylalanine. All other compounds had negligible effects, and most were toxic at high concentrations. β-Phenylserine, a phenylalanine antagonist, actually prolonged the survival of chick heart cells but only if both phenylalanine and tyrosine were present. Similarly, optimal reversal of β-phenylserine toxicity was dependent on the presence of both amino acids. Although phenylalanine and tyrosine are not interconvertible in the present system, it has been shown that three phenylalanine antagonists, p-fluorophenylalanine, β-2-thienylalanine, and β-phenylserine, can be identified by their relationship to tyrosine, rather than to phenylalanine.

scholarly journals Amino acid uptake in isolated chick embryo heart cells. Effect of insulin

1969 ◽  
Vol 114 (1) ◽  
pp. 97-105 ◽  
Author(s):  
G. G. Guidotti ◽  
Britta Lüneburg ◽  
A. F. Borghetti
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Chick Embryo ◽  
Isolated Heart ◽  
Cardiac Cells ◽  
Cell Permeability ◽  
Heart Cells ◽  
Acid Uptake ◽  
Aminoisobutyric Acid ◽  
Isolated Heart Cells

1. The preparation of cell suspensions by treatment of chick embryo hearts with collagenase at various stages of development is described. 2. Measurements of oxygen consumption, incorporation of labelled leucine into protein and accumulation of labelled α-aminoisobutyric acid against a concentration gradient indicated a long-lasting viability of the isolated heart cells in vitro; a satisfactory preservation of subcellular structures, including plasma membrane, was assessed by electron-microscopic examination. 3. The rate of α-aminoisobutyric acid accumulation by cardiac cells isolated from hearts at different stages of embryological development decreased with aging; insulin stimulated the intracellular accumulation of this amino acid analogue. 4. Insulin increased the uptake by isolated heart cells of several 14C-labelled naturally occurring amino acids; however, the fraction of amino acid taken up by the cells that was recovered free intracellularly, and therefore the concentration ratio (between intracellular water and medium), was enhanced by the hormone only with glycine, proline, serine, threonine, histidine and methionine. When isolated heart cells were incubated in the presence of a mixture of labelled amino acids, the addition of insulin increased the disappearance of radioactivity from the medium. 5. The general pattern of amino acid transport (in the absence and in the presence of insulin) in isolated cardiac cells was similar to that found in intact hearts, suggesting that the biological preparation described in this paper might be useful for studies of cell permeability and insulin action.

scholarly journals Amino acid uptake in the developing chick embryo heart. The effect of insulin on glycine and leucine accumulation

1968 ◽  
Vol 107 (4) ◽  
pp. 575-580 ◽  
Author(s):  
G. G. Guidotti ◽  
G. Gaja ◽  
L. Loreti ◽  
G. Ragnotti ◽  
D. A. Rottenberg ◽  
...  
Keyword(s):  
Amino Acid ◽  
Chick Embryo ◽  
Concentration Ratio ◽  
Amino Acid Uptake ◽  
Acid Uptake ◽  
Experimental Conditions ◽  
Insulin Effect ◽  
Chick Embryo Heart ◽  
Embryo Heart

1. The accumulation of [1−14C]glycine and the uptake, accumulation, incorporation (into protein, lipid, glycogen) and oxidation of l-[1−14C]leucine in 5-day-old chick embryo hearts were investigated in vitro, and the effects of insulin, puromycin and 4-methyl-2-oxopentanoic acid on these processes were studied. 2. With glycine, the ratio of concentration of the labelled amino acid in the cell water to that in medium markedly exceeded unity. Insulin significantly increased this ratio. Puromycin did not prevent the insulin effect. 3. With leucine, the concentration ratio of the labelled amino acid between intracellular and extracellular water approached unity in the absence of puromycin and was doubled by its presence. In neither case did insulin substantially alter this ratio. The addition of 4-methyl-2-oxopentanoic acid had no effect in the absence of insulin, but produced a significant increase of the concentration ratio in the presence of the hormone. 4. Leucine uptake was increased slightly by insulin in all experimental conditions except in the presence of puromycin, where a more pronounced stimulation was observed. The hormone had no effect on the incorporation of the labelled amino acid into protein, but accelerated its oxidation to carbon dioxide; the latter effect was particularly evident in the presence of puromycin and disappeared after the addition of 4-methyl-2-oxopentanoic acid.

Regulation of amino acid transport in chick embryo heart cells

1972 ◽  
Vol 266 (2) ◽  
pp. 407-421 ◽  
Author(s):  
G.C. Gazzola ◽  
R. Franchi ◽  
V. Saibene ◽  
P. Ronchi ◽  
G.G. Guidotti
Keyword(s):  
Amino Acid ◽  
Chick Embryo ◽  
Amino Acid Transport ◽  
Heart Cells ◽  
Acid Transport ◽  
Chick Embryo Heart ◽  
Embryo Heart

COMPETITION BETWEEN AMINO ACIDS FOR TRANSPORT INTO EHRLICH ASCITES CARCINOMA CELLS

1961 ◽  
Vol 39 (11) ◽  
pp. 1717-1735 ◽  
Author(s):  
P. G. Scholefield
Keyword(s):  
Carbon Dioxide ◽  
Amino Acids ◽  
Amino Acid ◽  
Ehrlich Ascites Carcinoma ◽  
Carcinoma Cells ◽  
Transport Systems ◽  
Radioactive Carbon ◽  
Ehrlich Ascites ◽  
Competitive Inhibitors ◽  
Amino Acid Analogues

The cumulative entry of amino acids into Ehrlich ascites carcinoma cells is due to the presence of active transport systems, each with its own specific range of substrates. Several amino acids and amino acid analogues may have an affinity for the same transport system and thus may inhibit transport of other amino acids by acting as competitive inhibitors or competitive substrates. Loss of methionine from ascites cells takes place by a diffusion process which obeys Fick's law. Leucine accumulation by ascites cells is small and is increased on addition of certain other amino acids. The increase is not due to inhibition of leucine oxidation as increase in the rate of production of radioactive carbon dioxide from labeled leucine also occurs. Kinetic aspects of these results are discussed.

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