IGF-I and IGFBP-3 transport in the rat heart

Am J Physiol Endocrinol Metab. 2003 Jan;284(1):E237-9. doi: 10.1152/ajpendo.00336.2002.

Abstract

Specific binding of IGF-binding protein (IGFBP)-3 was shown to be present in the isolated, beating rat heart. The uptake of perfused (125)I-labeled IGF-I in the beating heart was decreased to 9% by blocking IGF-I binding sites with the IGF-I analog Long R(3) (LR(3)) IGF-I. When LR(3) was perfused with complexes of (125)I-IGF-I. IGFBP-3, uptake of (125)I-IGF-I was decreased to 41%, which was significantly greater than LR(3) and (125)I-IGF-I (41 vs. 9%). These data suggest that both microvessel IGF-I and IGFBP-3 binding sites contribute to the transport of IGF-I in the perfused rat heart. This also suggests a novel and plausible mechanism whereby circulating IGFs reach sites of IGF bioactivity.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Autoradiography
  • Binding Sites
  • Biological Transport
  • Cells, Cultured
  • Endothelium, Vascular / metabolism
  • Insulin-Like Growth Factor Binding Protein 3 / administration & dosage
  • Insulin-Like Growth Factor Binding Protein 3 / genetics
  • Insulin-Like Growth Factor Binding Protein 3 / metabolism*
  • Insulin-Like Growth Factor Binding Protein 4 / genetics
  • Insulin-Like Growth Factor Binding Protein 4 / metabolism
  • Insulin-Like Growth Factor I / administration & dosage
  • Insulin-Like Growth Factor I / metabolism*
  • Iodine Radioisotopes
  • Male
  • Microcirculation / metabolism
  • Myocardium / metabolism*
  • Rats
  • Rats, Sprague-Dawley
  • Recombinant Fusion Proteins / metabolism

Substances

  • Insulin-Like Growth Factor Binding Protein 3
  • Insulin-Like Growth Factor Binding Protein 4
  • Iodine Radioisotopes
  • Recombinant Fusion Proteins
  • Insulin-Like Growth Factor I