Sample site selection for tracer studies applying a unidirectional circulatory approach

Journal Article · Sat Aug 01 04:00:00 EDT 1987 · Am. J. Physiol.; (United States)

OSTI ID:6243960

Layman, D K; Wolfe, R R

The optimal arterial or venous sites for infusion and sampling during isotopic tracer studies have not been established. This study determined the relationship of plasma and tissue enrichment (E) when isotopes were infused in an artery and sampled from a vein (av mode) or infused in a vein and sampled from an artery (va mode). Adult dogs were given primed constant infusions of (3-/sup 13/C)lactate, (1-/sup 13/C)leucine, and /sup 14/C-labeled bicarbonate. Simultaneous samples were drawn from the vena cava, aortic arch, and breath. Tissue samples were removed from skeletal muscle, liver, kidney, and gut. Breath samples were analyzed for /sup 14/CO/sub 2/ by liquid scintillation counting and plasma isotopic enrichments of (/sup 13/C)lactate, (/sup 13/C)leucine, and alpha-(/sup 13/C)ketoisocaproate (KIC) were determined by gas chromatography-mass spectrometry. By using the va mode, the plasma E for lactate and leucine were 30-40% above tissue E. The av mode provided an accurate reflection of tissue E for lactate, which equilibrates rapidly with tissues, and a reasonable estimate for leucine, which exchanges more slowly. The isotopic enrichment of plasma KIC more directly reflected tissue leucine E than did plasma leucine E, and KIC enrichment was insensitive to sampling site. We also evaluated theoretically a circulatory model that predicts venous isotopic enrichments when the va mode is used. We conclude that the av mode is optimal but that the problems arising from use of the va mode can be overcome by use of a metabolic product (i.e., KIC) or by calculation of venous specific activity with our circulatory mode.

• Research Organization: Univ. of Illinois, Urbana
• OSTI ID: 6243960
• Journal Information: Am. J. Physiol.; (United States), Journal Name: Am. J. Physiol.; (United States) Vol. 253; ISSN AJPHA
• Country of Publication: United States
• Language: English

Related Subjects

551001* -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ACETATES
ACID CARBONATES
ALKALI METALS
AMINO ACIDS
ANIMALS
ARTERIES
BIOLOGICAL MATERIALS
BIOLOGICAL MODELS
BLOOD
BLOOD CIRCULATION
BLOOD PLASMA
BLOOD VESSELS
BODY
BODY FLUIDS
CARBON 13
CARBON 14 COMPOUNDS
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON ISOTOPES
CARBON OXIDES
CARBOXYLIC ACID SALTS
CARBOXYLIC ACIDS
CARDIOVASCULAR SYSTEM
CHALCOGENIDES
CHROMATOGRAPHY
COUNTING TECHNIQUES
DIGESTIVE SYSTEM
DOGS
ELEMENTS
EVEN-ODD NUCLEI
GAS CHROMATOGRAPHY
GASTROINTESTINAL TRACT
GLANDS
INFUSION
INTAKE
INTESTINES
ISOTOPE APPLICATIONS
ISOTOPES
KETO ACIDS
KIDNEYS
LABELLED COMPOUNDS
LEUCINE
LIGHT NUCLEI
LIVER
MAMMALS
MASS SPECTROSCOPY
MATERIALS
METALS
MUSCLES
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
OXIDES
OXYGEN COMPOUNDS
RESPIRATION
SCINTILLATION COUNTING
SEPARATION PROCESSES
SODIUM
SPECTROSCOPY
STABLE ISOTOPES
TRACER TECHNIQUES
VEINS
VERTEBRATES