Basolateral amino acid transport systems in the perfused exocrine pancreas: sodium-dependency and kinetic interactions between influx and efflux mechanisms

Mann, Giovanni E.; Peran, Suzana

doi:10.1016/0005-2736(86)90331-7

Cited by 40 publications

(18 citation statements)

References 29 publications

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“…Other features of L-leucine transport revealed a maximal acceleration of tracer efflux by low concentrations of extracellular L-leucine (see Tables 1 and 2), a phenomenon observed previously in the perfused salivary gland and pancreas (Mann & Yudilevich, 1984;Mann & Peran, 1986). We also noted that, unlike most amino acids, L-methionine and D-leucine were potent inhibitors of tracer efflux (Fig.…”

Section: Endothelial Cell Removal Of Serotonin and Dopaminesupporting

confidence: 80%

“…Lack of uptake for the system A-selective analogue 2-MeAlB and the negligible uptake for L-proline ( Table 1), suggest that system A is not expressed in umbilical vein endothelial cells. L-Serine transport was markedly dependent upon extracellular sodium, as expected if uptake occurred primarily via a Na+-dependent system ASC (alanine-serine-cysteine) and not a Na+-independent system as recently described in erythrocytes (Fincham, Mason, Paterson & Young, 1987) and the exocrine pancreas (Mann & Peran, 1986).…”

Section: Endothelial Cell Amino Acid Transportsupporting

confidence: 72%

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Expression of amino acid transport systems in cultured human umbilical vein endothelial cells.

Mann

Pearson

Sheriff

et al. 1989

The Journal of Physiology

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SUMMARY1. Nutrient transport in cultured human umbilical vein endothelial cells was characterized using a rapid dual-isotope dilution technique. Microcarrier beads with confluent endothelial cells were perfused in small columns, and uptake and efflux were assessed relative to D-mannitol (extracellular tracer) during a single transit through the column.2. At tracer concentrations significant unidirectional uptakes were measured for L-leucine (53 + 2 %), L-phenylalanine (73 + 2 %), L-serine (40 +4%), L-arginine (42 + 3 %) and L-ornithine (26 + 3 %). Uptake for L-proline, D-glucose, dopamine and serotonin was lower (6-10 %), whereas uptake for the system A analogue 2-methylaminoisobutyric acid (2-MeAIB) was negligible. Uptakes rapidly decreased with time due to tracer efflux. 6. Our results provide the first evidence that cultured human endothelial cells of venous origin express a saturable transport system for large neutral amino acids resembling system L described in brain microvascular endothelium. Detection of Na+-dependent and Na+-independent L-arginine uptake is of interest in view of recent reports that this cationic amino acid may be the physiological precursor for nitric oxide released by endothelium.

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Section: Endothelial Cell Removal Of Serotonin and Dopaminesupporting

confidence: 80%

Section: Endothelial Cell Amino Acid Transportsupporting

confidence: 72%

Expression of amino acid transport systems in cultured human umbilical vein endothelial cells.

Mann

Pearson

Sheriff

et al. 1989

The Journal of Physiology

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“…Pancreatic acinar cells which have a diameter of 15-30/xm are particularly suitable for studying Na+-coupled amino acid transport since they have a high rate of protein synthesis and accumulate amino acids with high efficiency (Wheeler, Lukins & Gy6rgy, 1949;Hokin, 1951;B6gin & Scholefield, 1964B6gin & Scholefield, , 1965aCheneval &. Johnstone, 1974Petersen, 1976;Tyrakowski, Milutinovid & Schulz, 1978;Schulz & Ullrich, 1979;lwamoto & Williams, 1980;Iwatsuki & Petersen, 1980a,b;Laugier & Petersen, 1981;Mann & Peran, 1986) Depending on the direction of the driving force, cJt ass window fhermostoted copper block microscope objecfive Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

Electrogenic properties of the sodium-alanine cotransporter in pancreatic acinar cells: I. Tight-seal whole-cell recordings

1986

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Electrical currents associated with sodium-coupled alanine transport in mouse pancreatic acinar cells were studied using the method of whole-cell recording with patch pipettes. Single cells or small clusters of (electrically coupled) cells were isolated by collagenase treatment. The composition of the intracellular solution could be controlled by internal perfusion of the patch pipette. In this way both inward and outward currents could be measured under "zero-trans" conditions, i.e., with finite concentrations of sodium and L-alanine on one side and zero concentrations on the other. Inward and outward currents for equal but opposite concentration gradients were found to be of similar magnitude, meaning that the cotransporter is functionally nearly symmetric. The dependence of current on the concentrations of sodium and L-alanine exhibited a Michaelis-Menten behavior. From the sodium-concentration dependence of current as well as from the reversal potential of the current in the presence of an alanine-concentration gradient, a sodium/alanine stoichiometric ratio of 1:1 can be inferred. The finding that N-methylated amino acids may substitute for L-alanine, as well as the observed pH dependence of currents indicate that the pancreatic alanine transport system is similar to (or identical with) the "A-system" which is widespread in animal cells. The transport system is tightly coupled with respect to Na+; alanine-coupled inward flow of Na+ is at least 30 times higher than uncoupled Na+ flow mediated by the cotransporter. The current-voltage characteristic of the cotransporter could be (approximately) determined from the difference of transmembrane current in the presence and in the absence of L-alanine. The sodium-concentration dependence of the current-voltage characteristic indicates that a Na+ ion approaching the binding site from the extracellular medium has to cross part of the transmembrane electric field.

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“…Zn uptake shares nearly all these characteristics with Pb uptake, although its absolute rate is much less (Simons, 1986 The high influx rate of extracellular amino acids into the pancreas is mediated by several transport systems and appears to be balanced by a nearly equal capacity for efflux (Mann & Peran, 1986). In the present experiments we have employed a loading and wash-out technique (Boyd & Parsons, 1979) (Mann & Peran, 1986) it would appear that vascular dilution reduced the 100 mm injectate amino acid concentration to 8-10 mm.…”

mentioning

confidence: 99%

“…In the present experiments we have employed a loading and wash-out technique (Boyd & Parsons, 1979) (Mann & Peran, 1986) it would appear that vascular dilution reduced the 100 mm injectate amino acid concentration to 8-10 mm. Since the maximum vascular amino acid concentration coincided with stimulated tracer efflux (7 s), this suggests a substrate selective trans-stimulation of efflux.…”

mentioning

confidence: 99%

Proceedings of the Physiological Society, 25‐26 July 1986, Cambridge Meeting: Communications

1986

The Journal of Physiology

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Basolateral amino acid transport systems in the perfused exocrine pancreas: sodium-dependency and kinetic interactions between influx and efflux mechanisms

Cited by 40 publications

References 29 publications

Expression of amino acid transport systems in cultured human umbilical vein endothelial cells.

Expression of amino acid transport systems in cultured human umbilical vein endothelial cells.

Electrogenic properties of the sodium-alanine cotransporter in pancreatic acinar cells: I. Tight-seal whole-cell recordings

Proceedings of the Physiological Society, 25‐26 July 1986, Cambridge Meeting: Communications

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