Design of experiments using isotopes for the determination of the rates of disposal of blood-borne substrates in vivo with special reference to glucose, ketone bodies, free fatty acids, and proteins

Journal Article · Thu Nov 01 00:00:00 EST 1973 · Biophys. J., v. 136, no. 3, pp. 503-518

OSTI ID:4346397

Heath, D F; Barton, R N

(R) of blood-borne substrates in vivo by isotope experiments involve estimating the specific radioactivity (S) of the substrate in blood either after single intravenous injection of labeled substrate or during its infusion at a constant rate. The value of R is calculated from the S-time curve, usually by assuming: (i) a metabolic steady state with respect to substrate, (ii) the passage of all substrate through the blood, and (iii) the absence of certain types of recycling via blood. In a theoretical investigation, it is shown how experiments can be performed and R calculated from analyses of blood when one or more of the above assumptions is unjustified, by using glucose, ketone bodies, plasma free fatty acids, and proteins as examples. lt is pointed out that in general the methods require single injection procedures, with estimation of the total quantity of label in the substrate in blood and the substrate concentration instead of only S. Such values give estimates of R with standard errors even when only one blood specimen is taken from each of a group of animals, as is convenient when working with small animals or substrates in low concentration, and when the animals are in a non-steady state in which constant infusion procedures are invalid. Similar methods give the fraction of label injected as one compound that passes through another (the isotopic yield). It is shown that the methods are not always applicable, and cannot be applied to plasma proteins in some pathological conditions. A questionnaire for assessing their applicability is given. (auth)

• Research Organization: Medical Research Council, Carshalton, Eng.
• NSA Number: NSA-29-016104
• OSTI ID: 4346397
• Journal Information: Biophys. J., v. 136, no. 3, pp. 503-518, Other Information: Orig. Receipt Date: 30-JUN-74; Bib. Info. Source: UK (United Kingdom (sent to DOE from))
• Country of Publication: United Kingdom
• Language: English

Related Subjects

N48830* -Life Sciences-New Tracer Techniques-Other
*BLOOD CIRCULATION- TRACER TECHNIQUES
BLOOD PLASMA
CARBOXYLIC ACIDS
GLUCOSE
IN VIVO
INTRAVENOUS INJECTION
ISOTOPIC EXCHANGE
KETONES
LABELLED COMPOUNDS
LABELLING
MATHEMATICAL MODELS
METABOLISM
PROTEINS
RADIONUCLIDE KINETICS
SUBSTRATES
TIME DEPENDENCE