Measurement of lactate formation from glucose using (6- sup 3 H)- and (6- sup 14 C)glucose in humans

Journal Article · Sat Sep 01 00:00:00 EDT 1990 · American Journal of Physiology; (USA)

OSTI ID:6510932

Virkamaeki, A P; Puhakainen, I; Nurjhan, N; Gerich, J E; Yki-Jaervinen, H ^[1]

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1. Helsinki Univ. (Finland)

To assess the validity of determining the origin of plasma lactate from the ratio of lactate and glucose specific activities (SA) during infusion of labeled glucose, normal subjects received infusions of (6-3H)- and (6-14C)glucose for 4 h after a 12 h fast, and, on another day, cold glucose labeled with both tracers during 4-6 h of hyperinsulinemia (approximately 650 microU/ml). Basally, less lactate was derived from plasma glucose when measured with (6-3H)glucose (27 +/- 2%) than with (6-14C)glucose (40 +/- 2%, P less than 0.001). Insulin did not increase the percent of lactate derived from plasma glucose when measured with (6-3H)glucose (29 +/- 2%) but did increase when measured with (6-14C)glucose (60 +/- 4%). The arterialized blood (A) (3H)lactate SA was 30-40% higher (P less than 0.01) than deep venous blood (V) (3H)lactate SA, whereas A and V (14C)lactate SA were similar. During conversion of alanine to lactate with glutamic-pyruvic transaminase (GPT) and lactate dehydrogenase (LDH) in vitro, 32 +/- 2% of 3H in (3-3H)alanine was found in water and 68 +/- 2% in lactate. During infusion of (6-3H)- and (6-14C)glucose, the ratio of (14C)alanine to lactate SA (0.88 +/- 0.05) was less than the ratio of (3H)alanine to lactate SA (0.31 +/- 0.03, P less than 0.001). In conclusion (1) loss of 3H relative to 14C from position 6 in glucose occurs during lactate formation in extrahepatic tissues possibly due to the GPT reaction (alanine conversion to pyruvate), and (2) even under supraphysiologic hyperinsulinemic conditions not all of plasma lactate originates from plasma glucose.

• OSTI ID: 6510932
• Journal Information: American Journal of Physiology; (USA), Journal Name: American Journal of Physiology; (USA) Vol. 259; 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
AMINOTRANSFERASES
ANIMALS
BIOSYNTHESIS
BLOOD FLOW
CARBOHYDRATES
CARBON 14 COMPOUNDS
CARBOXYLIC ACID SALTS
CARBOXYLIC ACIDS
ENZYMES
FASTING
GLUCOSE
HEMIACETAL DEHYDROGENASES
HEXOSES
HORMONES
HYDROGEN COMPOUNDS
INSULIN
ISOTOPE APPLICATIONS
ISOTOPE DILUTION
LABELLED COMPOUNDS
LACTATE DEHYDROGENASE
LACTATES
MAMMALS
MAN
METABOLISM
MONOSACCHARIDES
NITROGEN TRANSFERASES
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXIDOREDUCTASES
PEPTIDE HORMONES
PRIMATES
SACCHARIDES
SYNTHESIS
TRACER TECHNIQUES
TRANSFERASES
TRITIUM COMPOUNDS
VERTEBRATES