Tracer measured substrate turnover requires arterial sampling downstream of infusion site

Conference · Wed Mar 05 04:00:00 EST 1986 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:7119069

Stanley, W C; Neese, R A; Gertz, E W; Wisneski, J A; Morris, D L; Brooks, G A

Measurement of metabolite turnover (Rt) with radioactive tracers is done by either infusing tracer venously and sampling specific activity (SA) arterially (V-A modes), or by infusing into the aorta and sampling venous blood (A-V mode). Using the Fick principle, the necessity for using the V-A mode can be demonstrated. If tracer is infused into the left ventricle, in a steady state the Rt is the product of arterial trace concentration, the cardiac output, and the tracer extraction ratio for the whole body. This is expressed as: Rt = Ca x Qx ((*Ca - *Cv)/*Ca) (Eq1) where C=trace concentration (..mu..mol/ml), *C=tracer conc. (dpm/ml), a=arterial, v-=mixed venous, and Q=cardiac output (ml/min). Rearranging the equation: Rt = Qx(*Ca - *Cv)/SAa = F/SAa (Eq2) where SAa is *Ca/Ca, and Qx (*Ca-*Cv) equals the infusion rate (F). The authors compared Eqs1 and 2 (Rt = F/SAa) in 3 anesthetized dogs in which (1-/sup 14/C) lactate was infused into the left ventricle, and blood was sampled arterially downstream from the infusion site and in the pulmonary artery. Eqs 1 and 2 gave similar results for Rt (45.9 vs. 43.9 ..mu..mol/kg min), while substituting SAv for SAa (A-V mode) into Eq 2 gave a higher Rt (53.6). When SAv (A-V mode) is used, the specific activity seen by the tissues (SAa) is not considered in the calculation of Rt. Therefore, only the V-A mode meets the requirements for tracer measured metabolite turnover.

• Research Organization: Univ. of California, San Francisco
• OSTI ID: 7119069
• Report Number(s): CONF-8604222-
• Conference Information: Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Journal Volume: 45:4
• Country of Publication: United States
• Language: English

Related Subjects

550501* -- Metabolism-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
AORTA
ARTERIES
BIOLOGICAL MATERIALS
BLOOD
BLOOD VESSELS
BODY
BODY FLUIDS
CARBON 14 COMPOUNDS
CARBOXYLIC ACID SALTS
CARDIOVASCULAR SYSTEM
DOGS
EQUATIONS
EVALUATION
HEART
INFUSION
INTAKE
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LACTATES
MAMMALS
MATERIALS
METABOLISM
METABOLITES
ORGANS
TRACER TECHNIQUES
VEINS
VERTEBRATES