Insulin-sensitive tyrosine kinase is increased in livers of adult obese Zucker rats: Correction with prolonged fasting

J. Shemer, A. Ota, Martin L Adamo, D. LeRoith

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Adult obese Zucker rats (fa,fa) are hyperinsulinemic and insulin resistant. Specific insulin binding to crude membranes prepared from livers was 2.8% (per mg protein) in fatty animals compared with 7.9% in homozygous lean (Fa,Fa) and 9.0% in heterozygous lean (Fa,fa) animals. Insulin binding increased in liver membranes from fatty animals after a 72-h fast to 6.4%. The reduced insulin binding in livers from fatty rats was associated with elevated insulin-sensitive tyrosine kinase activity, which fell towards control values after the fast. The elevated tyrosine kinase activity was associated with an increased maximum velocity (V(max)) without a change in Michaelis-Menten constant (K(m)) for its substrates, ATP and poly(Glu,Tyr)4:1. These findings suggest that, in adult fatty rats, insulin-sensitive tyrosine kinase has increased intrinsic activity. Further, the effect of the prolonged fast on both insulin binding and kinase activity, suggest that in this model environmental factors, and not necessarily a genetic abnormality, may regulate liver insulin receptors and their kinase. Whether the inverse relationship of the kinase and insulin receptor number is the result of a compensatory mechanism remains to be elucidated.

Original languageEnglish (US)
Pages (from-to)140-148
Number of pages9
JournalEndocrinology
Volume123
Issue number1
StatePublished - 1988
Externally publishedYes

Fingerprint

Zucker Rats
Protein-Tyrosine Kinases
Fasting
Insulin
Liver
Phosphotransferases
Insulin Receptor
Fatty Liver
Membranes
Adenosine Triphosphate

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

Cite this

Insulin-sensitive tyrosine kinase is increased in livers of adult obese Zucker rats : Correction with prolonged fasting. / Shemer, J.; Ota, A.; Adamo, Martin L; LeRoith, D.

In: Endocrinology, Vol. 123, No. 1, 1988, p. 140-148.

Research output: Contribution to journalArticle

Shemer, J. ; Ota, A. ; Adamo, Martin L ; LeRoith, D. / Insulin-sensitive tyrosine kinase is increased in livers of adult obese Zucker rats : Correction with prolonged fasting. In: Endocrinology. 1988 ; Vol. 123, No. 1. pp. 140-148.
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