Constant specific activity input allows reconstruction of endogenous glucose concentration in non-steady state.

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  • Author(s): Cobelli C;Cobelli C; Toffolo G
  • Source:
    The American journal of physiology [Am J Physiol] 1990 Jun; Vol. 258 (6 Pt 1), pp. E1037-40.
  • Publication Type:
    Journal Article; Research Support, Non-U.S. Gov't
  • Language:
    English
  • Additional Information
    • Source:
      Publisher: American Physiological Society Country of Publication: United States NLM ID: 0370511 Publication Model: Print Cited Medium: Print ISSN: 0002-9513 (Print) Linking ISSN: 00029513 NLM ISO Abbreviation: Am J Physiol Subsets: MEDLINE
    • Publication Information:
      Publication: Bethesda, MD : American Physiological Society
      Original Publication: Washington [etc.] American Physiological Society.
    • Subject Terms:
      Models, Biological*; Glucose/*metabolism ; Liver/*metabolism; Animals ; Dogs ; Mathematics ; Radioisotope Dilution Technique
    • Abstract:
      In vivo studies on the glucose system often require its perturbation by an exogenous input of glucose, whereas glucose turnover is assessed by infusing a glucose tracer. The constant infusion represents the usual format of tracer administration, but it has no clear advantage other than simplicity. Here we propose a different tracer infusion format. It consists of infusing the tracer in parallel with unlabeled glucose so as to maintain a constant specific activity in the infusate. This protocol does not increase experimental complexity and provides new information on the glucose system in non-steady state by allowing reconstruction of the endogenous component of glucose concentration. This reconstruction only requires very general assumptions, such as tracer-tracee indistinguishability and mass conservation; in particular it is independent of the glucose model structure, i.e., number of compartments and their interconnections. A proof of the result is given for a general nonlinear model of the glucose system. The constant specific activity input is also advantageous for non-steady-state calculations, because it reduces the variation in the measured plasma glucose specific activity. The glucose system has served as the prototype, but the protocol is applicable to other blood-borne substances. The radioactive tracer case has been considered, but the same results apply to stable isotope tracers as well; in this case they also become relevant in a somewhat different context, i.e., kinetic studies in steady state.
    • Accession Number:
      IY9XDZ35W2 (Glucose)
    • Publication Date:
      Date Created: 19900601 Date Completed: 19900802 Latest Revision: 20171213
    • Publication Date:
      20240829
    • Accession Number:
      10.1152/ajpendo.1990.258.6.E1037
    • Accession Number:
      2193529