Vascular transport of insulin to rat cardiac muscle. Central role of the capillary endothelium

J Clin Invest. 1988 Apr;81(4):1225-33. doi: 10.1172/JCI113439.


Using intact, beating hearts, we have assessed the interaction of insulin with capillary endothelium and the subsequent appearance of insulin in cardiac muscle. Rat hearts were perfused with 125I-insulin (10(-10) M) alone or in combination with unlabeled insulin (10(-9)-10(-5) M). 125I grains (shown to represent greater than 90% intact insulin) over both capillary endothelium and cardiac muscle decreased in a dose-dependent manner when hearts were co-perfused with labeled insulin and increasing concentrations of unlabeled insulin. Perfusion of 125I-desoctapeptide (DOP) insulin, a low affinity insulin analogue, with unlabeled insulin (10(-9)-10(-5) M) had no effect on the appearance of 125I-DOP insulin over microvessel endothelium and muscle. When capillary receptors were first destroyed by trypsin treatment or blocked by anti-receptor antibodies, the appearance of 125I-insulin in cardiac muscle decreased proportional to the inhibition of insulin binding to the capillary receptors. We conclude that insulin binding to capillary endothelial receptors is a central step in the transport of intravascular insulin to rat cardiac muscle.

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
  • Biological Transport
  • Capillaries / metabolism
  • Coronary Vessels / metabolism
  • Endothelium, Vascular / metabolism*
  • Insulin / metabolism*
  • Intercellular Junctions / physiology
  • Male
  • Microscopy, Electron
  • Myocardium / metabolism*
  • Rats
  • Receptor, Insulin / metabolism*
  • Trypsin


  • Insulin
  • Receptor, Insulin
  • Trypsin