Net interorgan transport of L-glutamate in rats occurs via the plasma, not via erythrocytes

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Glutamate is concentrated within RBC, but this intracellular glutamate is often ignored in studies of glutamate metabolism in vivo. The objective of this work was to determine the size of the plasma and cellular glutamate pools in rat blood and to clarify the role of RBC in the interorgan transport of glutamate. Approximately 20% of whole-blood glutamate was associated with isolated RBC membranes, but this was easily removed by washing with high salt solutions. Arterial plasma glutamate levels were relatively stable and did not show marked differences with starvation, streptozotocin diabetes or feeding 60% casein diets. In rats fed 5% casein, the plasma glutamate level was slightly higher (P < 0.05) than in most other groups. In contrast, RBC glutamate levels showed considerable variation. In rats consuming 5% casein, cellular glutamate levels were ∼ 100% higher (P < 0.05) than in control, starved, diabetic or 20 or 60% casein-fed rats. Cellular glutamate levels were also higher (P < 0.05) in rats fed 60% casein than in those consuming 20% casein or the control diet. Rat erythrocytes in vitro did not take up or release free glutamate, confirming that they do not possess a glutamate transporter. Arteriovenous difference measurements across the portal drained viscera indicated a net glutamate release into the portal vein in control, 60% casein-fed and diabetic rats. In all cases, the net change in blood glutamate across the tissue occurred via the plasma, with no change in cellular glutamate levels. Therefore analyses of glutamate metabolism in rats in vivo may be made confidently using measurements of either whole-blood or plasma glutamate concentrations.

Original languageEnglish (US)
Pages (from-to)952-956
Number of pages5
JournalJournal of Nutrition
Volume132
Issue number5
StatePublished - May 20 2002

Fingerprint

glutamates
Glutamic Acid
erythrocytes
Erythrocytes
rats
Caseins
casein
blood
Diet
Amino Acid Transport System X-AG
Experimental Diabetes Mellitus
Viscera
portal vein
metabolism
streptozotocin
Portal Vein
animal organs
Starvation
diet
washing

All Science Journal Classification (ASJC) codes

  • Medicine (miscellaneous)
  • Nutrition and Dietetics

Keywords

  • Amino acids
  • Blood
  • Erythrocytes
  • Glutamate
  • Plasma
  • Rats

Cite this

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title = "Net interorgan transport of L-glutamate in rats occurs via the plasma, not via erythrocytes",
abstract = "Glutamate is concentrated within RBC, but this intracellular glutamate is often ignored in studies of glutamate metabolism in vivo. The objective of this work was to determine the size of the plasma and cellular glutamate pools in rat blood and to clarify the role of RBC in the interorgan transport of glutamate. Approximately 20{\%} of whole-blood glutamate was associated with isolated RBC membranes, but this was easily removed by washing with high salt solutions. Arterial plasma glutamate levels were relatively stable and did not show marked differences with starvation, streptozotocin diabetes or feeding 60{\%} casein diets. In rats fed 5{\%} casein, the plasma glutamate level was slightly higher (P < 0.05) than in most other groups. In contrast, RBC glutamate levels showed considerable variation. In rats consuming 5{\%} casein, cellular glutamate levels were ∼ 100{\%} higher (P < 0.05) than in control, starved, diabetic or 20 or 60{\%} casein-fed rats. Cellular glutamate levels were also higher (P < 0.05) in rats fed 60{\%} casein than in those consuming 20{\%} casein or the control diet. Rat erythrocytes in vitro did not take up or release free glutamate, confirming that they do not possess a glutamate transporter. Arteriovenous difference measurements across the portal drained viscera indicated a net glutamate release into the portal vein in control, 60{\%} casein-fed and diabetic rats. In all cases, the net change in blood glutamate across the tissue occurred via the plasma, with no change in cellular glutamate levels. Therefore analyses of glutamate metabolism in rats in vivo may be made confidently using measurements of either whole-blood or plasma glutamate concentrations.",
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Net interorgan transport of L-glutamate in rats occurs via the plasma, not via erythrocytes. / Watford, Malcolm.

In: Journal of Nutrition, Vol. 132, No. 5, 20.05.2002, p. 952-956.

Research output: Contribution to journalArticle

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