Contribution of liver and skeletal muscle to alanine and lactate metabolism in humans

Journal Article · Wed Oct 31 23:00:00 EST 1990 · American Journal of Physiology; (USA)

OSTI ID:6071738

Consoli, A; Nurjhan, N; Reilly, Jr, J J; Bier, D M; Gerich, J E ^[1]

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1. Univ. of Pittsburgh School of Medicine, PA (USA)

To quantitate alanine and lactate gluconeogenesis in postabsorptive humans and to test the hypothesis that muscle is the principal source of these precursors, we infused normal volunteers with (3-14C)lactate, (3-13C)alanine, and (6-3H)glucose and calculated alanine and lactate incorporation into plasma glucose corrected for tricarboxylic acid cycle carbon exchange, the systemic appearance of these substrates, and their forearm fractional extraction, uptake, and release. Forearm alanine and lactate fractional extraction averaged 37 +/- 3 and 27 +/- 2%, respectively; muscle alanine release (2.94 +/- 0.27 mumol.kg body wt-1.min-1) accounted for approximately 70% of its systemic appearance (4.18 +/- 0.31 mumol.kg body wt-1.min-1); muscle lactate release (5.51 +/- 0.42 mumol.kg body wt-1.min-1) accounted for approximately 40% of its systemic appearance (12.66 +/- 0.77 mumol.kg body wt-1.min-1); muscle alanine and lactate uptake (1.60 +/- 0.7 and 3.29 +/- 0.36 mumol.kg body wt-1.min-1, respectively) accounted for approximately 30% of their overall disappearance from plasma, whereas alanine and lactate incorporation into plasma glucose (1.83 +/- 0.20 and 4.24 +/- 0.44 mumol.kg body wt-1.min-1, respectively) accounted for approximately 50% of their disappearance from plasma. We therefore conclude that muscle is the major source of plasma alanine and lactate in postabsorptive humans and that factors regulating their release from muscle may thus exert an important influence on hepatic gluconeogenesis.

• OSTI ID: 6071738
• Journal Information: American Journal of Physiology; (USA), Journal Name: American Journal of Physiology; (USA) Vol. 259:5 Pt 1; ISSN 0002-9513; ISSN AJPHA
• Country of Publication: United States
• Language: English

Related Subjects

550501* -- Metabolism-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALANINES
ALDEHYDES
AMINO ACIDS
ANIMALS
BODY
CARBOHYDRATES
CARBON 13
CARBON 14 COMPOUNDS
CARBON ISOTOPES
CARBOXYLIC ACID SALTS
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
EVEN-ODD NUCLEI
GLUCOSE
HEXOSES
ISOTOPE APPLICATIONS
ISOTOPES
LABELLED COMPOUNDS
LACTATES
LIGHT NUCLEI
MAMMALS
MAN
METABOLISM
MONOSACCHARIDES
MUSCLES
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
PRECURSOR
PRIMATES
REDOX REACTIONS
SACCHARIDES
SKELETON
STABLE ISOTOPES
TRACER TECHNIQUES
VERTEBRATES