Characteristics and regulation of hepatic glutamine transport.

B. Bode, B. K. Tamarappoo, Mark E Mailliard, M. S. Kilberg

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

Glutamine is an important amino acid because of its key role in the transfer of both carbon and nitrogen between tissues in the body. Specific tissues are usually associated with either net synthesis or net utilization of glutamine, but the liver plays a central role in glutamine homeostasis, in that it can shift to function in either capacity. This capability, along with the localization of urea biosynthesis in the periportal hepatocytes, focuses attention on the transport mechanisms in hepatocytes for uptake and release of glutamine. Active transport of glutamine by hepatocytes is mediated by a Na(+)-dependent activity termed system N, which exhibits a rather narrow substrate specificity mediating uptake of histidine and asparagine as well as of glutamine. This secondary active transport system allows for the net accumulation of glutamine against a concentration gradient and maintenance of intracellular concentrations of glutamine between 4 and 8 mM in the face of a plasma concentration of 0.6 mM. Utilization of the Na+ electrochemical gradient as a driving force ensures that the system N carrier catalyzes a unidirectional transport event favoring the cytoplasm. It is obvious from the glutamine gradient across the plasma membrane that efflux of this amino acid is typically slower than accumulation; measurement of saturable, Na(+)-independent glutamine transport by system L substantiates this proposal. However, it is clear that under certain metabolic conditions the liver represents a source of glutamine for other tissues in the body and net efflux must occur. The system N transport activity in hepatocytes is regulated by hormones such as insulin, glucagon, and glucocorticoids, as demonstrated both in vivo and in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

Original languageEnglish (US)
JournalJournal of Parenteral and Enteral Nutrition
Volume14
Issue number4 Suppl
StatePublished - Jul 1 1990

Fingerprint

Glutamine
glutamine
liver
Liver
hepatocytes
Hepatocytes
active transport
Active Biological Transport
uptake mechanisms
Amino Acids
amino acids
Asparagine
glucagon
asparagine
substrate specificity
Substrate Specificity
glucocorticoids
Glucagon
histidine
Histidine

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Nutrition and Dietetics

Cite this

Characteristics and regulation of hepatic glutamine transport. / Bode, B.; Tamarappoo, B. K.; Mailliard, Mark E; Kilberg, M. S.

In: Journal of Parenteral and Enteral Nutrition, Vol. 14, No. 4 Suppl, 01.07.1990.

Research output: Contribution to journalArticle

@article{cf0aebc5e69440d19f68dc1369bba236,
title = "Characteristics and regulation of hepatic glutamine transport.",
abstract = "Glutamine is an important amino acid because of its key role in the transfer of both carbon and nitrogen between tissues in the body. Specific tissues are usually associated with either net synthesis or net utilization of glutamine, but the liver plays a central role in glutamine homeostasis, in that it can shift to function in either capacity. This capability, along with the localization of urea biosynthesis in the periportal hepatocytes, focuses attention on the transport mechanisms in hepatocytes for uptake and release of glutamine. Active transport of glutamine by hepatocytes is mediated by a Na(+)-dependent activity termed system N, which exhibits a rather narrow substrate specificity mediating uptake of histidine and asparagine as well as of glutamine. This secondary active transport system allows for the net accumulation of glutamine against a concentration gradient and maintenance of intracellular concentrations of glutamine between 4 and 8 mM in the face of a plasma concentration of 0.6 mM. Utilization of the Na+ electrochemical gradient as a driving force ensures that the system N carrier catalyzes a unidirectional transport event favoring the cytoplasm. It is obvious from the glutamine gradient across the plasma membrane that efflux of this amino acid is typically slower than accumulation; measurement of saturable, Na(+)-independent glutamine transport by system L substantiates this proposal. However, it is clear that under certain metabolic conditions the liver represents a source of glutamine for other tissues in the body and net efflux must occur. The system N transport activity in hepatocytes is regulated by hormones such as insulin, glucagon, and glucocorticoids, as demonstrated both in vivo and in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)",
author = "B. Bode and Tamarappoo, {B. K.} and Mailliard, {Mark E} and Kilberg, {M. S.}",
year = "1990",
month = "7",
day = "1",
language = "English (US)",
volume = "14",
journal = "Journal of Parenteral and Enteral Nutrition",
issn = "0148-6071",
publisher = "SAGE Publications Inc.",
number = "4 Suppl",

}

TY - JOUR

T1 - Characteristics and regulation of hepatic glutamine transport.

AU - Bode, B.

AU - Tamarappoo, B. K.

AU - Mailliard, Mark E

AU - Kilberg, M. S.

PY - 1990/7/1

Y1 - 1990/7/1

N2 - Glutamine is an important amino acid because of its key role in the transfer of both carbon and nitrogen between tissues in the body. Specific tissues are usually associated with either net synthesis or net utilization of glutamine, but the liver plays a central role in glutamine homeostasis, in that it can shift to function in either capacity. This capability, along with the localization of urea biosynthesis in the periportal hepatocytes, focuses attention on the transport mechanisms in hepatocytes for uptake and release of glutamine. Active transport of glutamine by hepatocytes is mediated by a Na(+)-dependent activity termed system N, which exhibits a rather narrow substrate specificity mediating uptake of histidine and asparagine as well as of glutamine. This secondary active transport system allows for the net accumulation of glutamine against a concentration gradient and maintenance of intracellular concentrations of glutamine between 4 and 8 mM in the face of a plasma concentration of 0.6 mM. Utilization of the Na+ electrochemical gradient as a driving force ensures that the system N carrier catalyzes a unidirectional transport event favoring the cytoplasm. It is obvious from the glutamine gradient across the plasma membrane that efflux of this amino acid is typically slower than accumulation; measurement of saturable, Na(+)-independent glutamine transport by system L substantiates this proposal. However, it is clear that under certain metabolic conditions the liver represents a source of glutamine for other tissues in the body and net efflux must occur. The system N transport activity in hepatocytes is regulated by hormones such as insulin, glucagon, and glucocorticoids, as demonstrated both in vivo and in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

AB - Glutamine is an important amino acid because of its key role in the transfer of both carbon and nitrogen between tissues in the body. Specific tissues are usually associated with either net synthesis or net utilization of glutamine, but the liver plays a central role in glutamine homeostasis, in that it can shift to function in either capacity. This capability, along with the localization of urea biosynthesis in the periportal hepatocytes, focuses attention on the transport mechanisms in hepatocytes for uptake and release of glutamine. Active transport of glutamine by hepatocytes is mediated by a Na(+)-dependent activity termed system N, which exhibits a rather narrow substrate specificity mediating uptake of histidine and asparagine as well as of glutamine. This secondary active transport system allows for the net accumulation of glutamine against a concentration gradient and maintenance of intracellular concentrations of glutamine between 4 and 8 mM in the face of a plasma concentration of 0.6 mM. Utilization of the Na+ electrochemical gradient as a driving force ensures that the system N carrier catalyzes a unidirectional transport event favoring the cytoplasm. It is obvious from the glutamine gradient across the plasma membrane that efflux of this amino acid is typically slower than accumulation; measurement of saturable, Na(+)-independent glutamine transport by system L substantiates this proposal. However, it is clear that under certain metabolic conditions the liver represents a source of glutamine for other tissues in the body and net efflux must occur. The system N transport activity in hepatocytes is regulated by hormones such as insulin, glucagon, and glucocorticoids, as demonstrated both in vivo and in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

UR - http://www.scopus.com/inward/record.url?scp=0025457589&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0025457589&partnerID=8YFLogxK

M3 - Article

VL - 14

JO - Journal of Parenteral and Enteral Nutrition

JF - Journal of Parenteral and Enteral Nutrition

SN - 0148-6071

IS - 4 Suppl

ER -