Transport of Glycine by Pigeon Red Cells<sup>*</sup>

Vidaver, George A.

doi:10.1021/bi00893a011

Cited by 164 publications

(66 citation statements)

References 14 publications

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“…Thus, intestinal transport (transmural) (4,6,7) and accumulation (4,8) of these solutes require the presence of Na in the mucosal bathing solution. Similar observations have been reported for sugar (9) and amino acid (10)(11)(12) accumulation by a variety of tissues other t h a n the intestine. In addition, active transport of sugars a n d / o r amino acids is associated with an increase in the rate of N a transport from mucosa to serosa in rabbit (13,14), rat (15), and h u m a n (16) small intestines.…”

supporting

confidence: 86%

Amino Acid and Sugar Transport in Rabbit Ileum

Schultz

Fuisz

Curran

1966

The Journal of General Physiology

222

103

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L-Alanine and 3-O-methyl-D-glucose accumulation by nmcosal strips from rabbit ileum has been investigated with particular emphasis on the interaction between Na and these transport processes. L-Alanine is rapidly accumulated by mucosal tissue and intracellular concentrations of approximately 50 m~ are reached within 30 rain when extracellular L-alanine concentration is 5 mM. Evidence is presented that intracellular alanine exists in an unbound, osmotically active form and that accumulation is an active transport process. In the absence of extracellular Na, the final ratio of intracellular to extracellular L-alanine does not differ significantly from unity and the rate of net uptake is markedly inhibited. Amino acid accumulation is also inhibited by 5 X 10 -~ M ouabain. 3-O-methyl-D-glucose accumulation by this preparation is similarly affected by ouabain and by incubation in a Na-free medium. The effects of amino acid accumulation, of ouabain, and of incubation in a Na-free medium on cell water content and intracellular Na and K concentrations have also been investigated. These results are discussed with reference to the two hypotheses which have been suggested to explain the interaction between Na and intestinal nonelectrolyte transport.In vitro preparations of m a m m a l i a n small intestine are capable of transporting sugars and amino acids from low concentrations in the mucosal solution to higher concentrations in the solution bathing the serosal side (1). Further, sugars (2) and amino acids (3, 4) are a c c u m u l a t e d by intestinal tissue and the concentrations of these solutes in tissue water m a y reach more t h a n ten times those in the surrounding media. These observations have led to the widely held view that intestinal sugar and amino acid absorption is the result of carrier-mediated processes which bring a b o u t uphill 1 transport from the mucosal solution into the cell followed by downhill exit from the cell across the serosal tissues (i).In recent years, interactions between Na and the transport of sugars and amino acids have been demonstrated. Thus, intestinal transport (transmural)The terms uphill or active transport will be used to denote movement against an electrochemical potential difference, according to the definition of Rosenberg (5). The term downhill denotes movement down an electrochemical potential difference.

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supporting

confidence: 86%

Amino Acid and Sugar Transport in Rabbit Ileum

Schultz

Fuisz

Curran

1966

The Journal of General Physiology

222

103

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“…The increase in affinity for alanine, seen in the presence of Na, arises from the operation of a second high affinity uptake mechanism. This situation is similar, if not identical, to that reported previously for avian and human erythrocytes (Vidaver, 1964;Ellory & Young, 1978) and Ehrlich ascites tumour cells (Christensen, 1975).…”

Section: Resultssupporting

confidence: 91%

A sodium‐indpendent low affinity transport system for neutral amino acids in rabbit ileal mucosa.

Paterson¹,

Sepúlveda²,

Smith³

1980

The Journal of Physiology

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SUIMMARY1. The kinetic parameters for serine, alanine and methionine uptake by rabbit ileal mucosa have been determined in the absence of Na.2. Uptake of all three amino acids took place through a single mediated system.The apparent Km values of serine, alanine and methionine for this system were equal to their respective apparent K1 values (approximately 89, 75 and 23 mm respectively).3. Autoradiography was used to measure the cellular location of alanine uptake by rabbit ileum. Approximately 80 % of the total uptake took place in the upper third of each villus. This uptake was reduced by 75 % either by removal of Na or addition of serine. The proportional distribution of Na-dependent and Naindependent alanine uptakes along the villus was found to be equal. 4. The kinetic properties of the low affinity uptake mechanism for neutral amino acids, seen in the absence of Na, were virtually identical with those of one of the uptake mechanisms seen previously in the presence of Na.5. The low affinity uptake mechanism appears to be Na-independent. It is suggested that the Na-coupled uptake of amino acid takes place through the high affinity system.

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“…The receptor site of System ASC binds the alkali ion at a closely specified point in juxtaposition t o the hydroxyl group of ordinary (trans) 4-hydroxyproline (4), whereas System A binds Na+ or Li+ at a different, less precisely localized point rather nearer the P-carbon atom of the bound amino acid substrate (5). The ASC system is conspicuous in immature and nucleated red cells (6)(7)(8), leukemia cells (9), and lymphocytes (10); it participates in placental transport (1 l), and in general it appears to be ubiquitous. ly all the neutral amino acids are to some degree transported by both of these systems, although in different proportions.…”

Section: :Jssmentioning

confidence: 99%

Amino acid transport systems in animal cells: Interrelations and energization

Christensen

1977

J Supramol Struct

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After summarizing the discrimination of the several transport systems for neutral amino acids in the cell of the higher animal, I discuss here the ways in which 2 dissimilar transport systems interact, so that one tends t o run torward for net entry and the other backwards for net exodus. An evaluation of the proposals for energization shows that uphill transport continues when neither alkali-ion gradients nor ATP levels are favorable. Evidence is presented that under these conditions a major contribution is made by another mode of energization, which may depend on the fueling of an oxidoreductase in the plasma membrane. This fueling may involve the export by the mitochondrion of the reducing equivalents of NADH by one of the known shuttles, e.g., the malate-aspartate shuttle. After depletion of the energy reserves in the Ehrlich cell by treating it with dinitrophenol plus iodoacetate concentrative uptake of test amino acids is restored by pyruvate, but in poor correlation with the restoration of alkali-ion gradients and ATP levels. This restoration by pyruvate but not by glucose is highly sensitive to rotenone. A combination of phenazine methosulfate and ascorbate will also produce transport restoration, before either the alkali-ion gradients or ATP levels have begun to rise. The restoration of transport applies to a model amino acid entering by the Na+-independent system, as well as to one entering by the principal Na+-dependent system, restoration being blocked by ouabain, despite the weak effect of ouabain on the alkali-ion gradients in the Ehrlich cell. Quinacrine terminates very quickly the uptake of model amino acids, before the alkali-ion gradients have begun to fall and before the ATP level has been halved. Quinacrine is also effective in blocking restoration of uphill transport by either pyruvate or the phenazine reagent. Preliminary results show that vesicles prepared from the plasma membrane of the Ehrlich cell quickly reduce cytochrome c or ferricyanide in the presence of NADH, and that the distribution of a test amino acid between the vesicle and its environment is influenced by NADH, quinacrine, and an uncoupling agent in ways consistent with the above proposal, assuming that a majority of the vesicles are everted.Key words: amino acid transport in animal cells, energization of transport systems, discrimination of transport systems, reverse operation of transport systems, Ehrlich cell, NADH dehydrogenase, alkali-ion gradients, phenazine methosulfate, ouabain TRANSPORT SYSTEMS AND THEIR INTERACTIONThe transport systems for neutral amino acids in the Ehrlich cell are taken t o be approximately representative of those of the cells of the higher animal in general, with more and more evidence supporting that interpretation. Most conspicuous are a broad-

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Transport of Glycine by Pigeon Red Cells^*

Cited by 164 publications

References 14 publications

Amino Acid and Sugar Transport in Rabbit Ileum

Amino Acid and Sugar Transport in Rabbit Ileum

A sodium‐indpendent low affinity transport system for neutral amino acids in rabbit ileal mucosa.

Amino acid transport systems in animal cells: Interrelations and energization

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Transport of Glycine by Pigeon Red Cells*

Cited by 164 publications

References 14 publications

Amino Acid and Sugar Transport in Rabbit Ileum

Amino Acid and Sugar Transport in Rabbit Ileum

A sodium‐indpendent low affinity transport system for neutral amino acids in rabbit ileal mucosa.

Amino acid transport systems in animal cells: Interrelations and energization

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Transport of Glycine by Pigeon Red Cells^*