Arterial KIC as marker of liver and muscle intracellular leucine pools in healthy and type 1 diabetic humans

R. Barazzoni, S. E. Meek, K. Ekberg, J. Wahren, K Sreekumaran Nair

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24 Citations (Scopus)

Abstract

In human protein turnover studies with isotopically labeled leucine (Leu) as a tracer, plasma ketoisocaproate (KIC) enrichment is extensively used as a surrogate measure of intracellular leucine enrichment. To test how accurately arterial ketoisocaproate (A-KIC) represents leucine isotopic enrichment in the hepatic (HV) and femoral veins (FV), which drain liver and muscle beds, we measured Leu and KIC enrichments in samples collected from HV, FV, and femoral artery (A) in 24 control and 6 type I diabetic subjects after a primed, continuous infusion of L-[1-13C,15N]-Leu. Studies were performed during insulin deprivation or insulin replacement in the diabetic group, whereas the effect of normal saline or three different doses of insulin infusion (0.25, 0.50, and 1 mU · kg-1 · min-1) were assessed in healthy controls. The ratios of baseline isotopic enrichments of A-KIC to HV Leu and FV Leu were 0.93 ± 0.01 and 0.94 ± 0.02, respectively, in normal subjects and 1.07 ± 0.04 and 1.05 ± 0.03, respectively, in diabetic subjects (P < 0.01, diabetic vs. normal subjects). Insulin did not change A- KIC-to-HV Leu ratios in either group, but the A-KIC-to-FV Leu ratio decreased during insulin infusion in normal subjects (P < 0.05). In conclusion, A-KIC represents a reliable surrogate measure of HV Leu enrichment at different levels of circulating insulin in humans. The present data support the use of A-KIC as a surrogate precursor pool for hepatic protein synthesis.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Volume277
Issue number2 40-2
StatePublished - Aug 1999

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Leucine
Liver
Muscle
Muscles
Femoral Vein
Insulin
Hepatic Veins
Femoral Artery
Proteins
Plasmas

Keywords

  • Ketoisocaproic acid
  • Precursor pool
  • Protein synthesis

ASJC Scopus subject areas

  • Biochemistry
  • Endocrinology
  • Physiology
  • Physiology (medical)

Cite this

Arterial KIC as marker of liver and muscle intracellular leucine pools in healthy and type 1 diabetic humans. / Barazzoni, R.; Meek, S. E.; Ekberg, K.; Wahren, J.; Nair, K Sreekumaran.

In: American Journal of Physiology - Endocrinology and Metabolism, Vol. 277, No. 2 40-2, 08.1999.

Research output: Contribution to journalArticle

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