Insulin and IGF-I binding and tyrosine kinase activity in fish heart

J Endocrinol. 1995 Jul;146(1):35-44. doi: 10.1677/joe.0.1460035.

Abstract

A study is presented of the binding of insulin and IGF-I to their respective receptors in the heart muscle of carp (Cyprinus carpio), coho salmon (Oncorhynchus kisutch), brown trout (Salmo trutta fario) and Sprague-Dawley rats. Receptor preparations were partially purified by wheat germ agglutinin affinity chromatography. Specific binding of insulin/100 mg cardiac muscle was much lower in fish (from 5.6 to 9.2%) than in rat (52.0 +/- 5.0%). In both carp and trout, insulin binding to the cardiac muscle receptor preparation was significantly higher than in the white skeletal muscle (3.4 +/- 0.3%, carp and 0.9 +/- 0.3%, trout) or in the red skeletal muscle of carp (5.5 +/- 0.8%). Specific binding of IGF-I/100 mg fish heart preparation ranged between 44 and 68%, surpassing IGF-I binding in the rat heart (20 +/- 6%). The affinity of IGF-I receptors in fish heart (Kd 0.17-0.19 nM) was higher than that in rat heart (Kd 0.40 +/- 0.05 nM) or insulin receptors in fish and rat heart preparations (0.25-0.72 nM). The IGF-I receptor binding was highly specific and required at least 100 nM insulin to cause any displacement of the bound ligand. Receptor tyrosine kinase activity could be stimulated in a dose-dependent manner by insulin and IGF-I, although in equimolar doses IGF-I was more potent than insulin. Maximum stimulation of tyrosine kinase activity (210-230%) in fish heart was in the same range as in other piscine tissues (150-260%) or in rat cardiac muscle (200-250%).

Publication types

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

MeSH terms

  • Animals
  • Carps
  • Fishes / metabolism*
  • Insulin / metabolism*
  • Insulin-Like Growth Factor I / metabolism*
  • Myocardium / enzymology
  • Myocardium / metabolism*
  • Protein Binding
  • Protein-Tyrosine Kinases / metabolism*
  • Rats
  • Rats, Sprague-Dawley
  • Receptor, IGF Type 1 / metabolism
  • Receptor, Insulin / metabolism
  • Salmon
  • Trout

Substances

  • Insulin
  • Insulin-Like Growth Factor I
  • Protein-Tyrosine Kinases
  • Receptor, IGF Type 1
  • Receptor, Insulin