Receptor-recycling model of clearance and distribution of insulin in the perfused mouse liver

H. Sato, T. Terasaki, H. Mizuguchi, K. Okumura, A. Tsuji

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)

Abstract

After perfusion of mouse livers with A14-125I-insulin for designated intervals, an acid-wash technique was employed to separately measure the surface-bound (Xs) and intracellular (Xi) A14-125I-insulin, as well as intracellular degradation products (Xdeg) of labelled insulin. From the perfusate concentrations (Cp) of A14-125I-insulin, the apparent intrinsic hepatic clearance of labelled insulin at a high dose (0.2 nmol/l) was shown to be 60% smaller than that at a low dose (0.018 nmol/l), indicating that the cellular uptake of insulin is remarkably nonlinear at the concentration range examined. From the time courses of Cp, Xs, Xi and Xdeg, the hepatic insulin disposition was shown to be largely accounted for by the receptor-mediated endocytosis. The observed data at the low dose were analysed to estimate biochemical parameters, (i.e., total receptor number, endocytotic rate constant and intracellular degradation rate constant) according to "receptor-recycling" and "non-receptor-recycling" models, using a computer-aided optimization procedure. The "receptor-recycling" model could not only adequately explain the Cp, Xs, Xi and Xdeg at the low dose, but also predict the Cp at the high dose. On the other hand, a "non-receptor-recycling" model, in which recycling of receptors was not assumed, could also explain the observed data at the low dose, but failed to predict the Cp at the high dose, indicating that the receptor recycling process is necessary to explain the hepatic insulin clearance at high insulin concentrations, at which hepatic insulin clearance should be limited by the rate of receptor recycling. However, the applicability of our model might be limited within the physiologic insulin concentrations, because of the negative co-operativity of insulin-receptor interaction and a high-capacity, non-degradative and more rapidly recycling pathway for receptors that may occur at high concentrations of insulin. In conclusion, we have developed a mathematical model of hepatic insulin clearance and distribution under physiological conditions, including receptor binding, receptor-mediated endocytosis and receptor recycling, which has been so far demonstrated using isolated hepatocytes.

Original languageEnglish
Pages (from-to)613-621
Number of pages9
JournalDiabetologia
Volume34
Issue number9
DOIs
Publication statusPublished - 1991 Sep

Keywords

  • Insulin
  • hepatic clearance
  • mouse liver perfusion
  • physiological model
  • receptor recycling
  • receptor-mediated endocytosis

ASJC Scopus subject areas

  • Internal Medicine
  • Endocrinology, Diabetes and Metabolism

Fingerprint Dive into the research topics of 'Receptor-recycling model of clearance and distribution of insulin in the perfused mouse liver'. Together they form a unique fingerprint.

Cite this