The IGF-I axis in kidney and skeletal muscle of potassium deficient rats

Kidney Int. 1997 Aug;52(2):363-70. doi: 10.1038/ki.1997.342.

Abstract

Potassium deficiency in the rat results in growth retardation, muscle wasting and renal hypertrophy. This study tests the thesis that K deficiency leads to tissue distinct changes in the local IGF-I system and cell sensitivity to IGF-I that favors renal enlargement on the one hand and impaired muscle growth on the other. In rats after eight days of K deficiency, compared to pair-fed control rats, food utilization and muscle and body wt gain were attenuated while the kidneys enlarged. In muscle GH receptor and IGF-I gene expression, IGF-I peptide and IGF binding protein-5 (IGFBP) levels were decreased. Together with reduced food utilization, these changes may contribute to the attenuated muscle growth. In the enlarged kidneys despite a fall in IGF-I mRNA level, IGF-I peptide concentration was increased more than twofold. This increase in IGF-I could be caused by the increase in kidney IGFBP-1 gene and protein expression and the decrease in kidney IGF-I degrading activity noted in K deficiency. Treatment with IGF-I failed to induce body or muscle growth, but induced a further increase in kidney size and enlargement of the spleen. Thus, in K deficiency the spontaneous increase in IGF-I levels in the kidney that is IGF-I sensitive may well be a cause of the renal hypertrophy.

Publication types

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

MeSH terms

  • Animals
  • Antibody Specificity
  • Blotting, Western
  • Body Weight
  • Cell Membrane / metabolism
  • Eating
  • Gene Expression / physiology
  • Insulin-Like Growth Factor Binding Protein 1 / genetics
  • Insulin-Like Growth Factor Binding Protein 1 / immunology
  • Insulin-Like Growth Factor I / analysis
  • Insulin-Like Growth Factor I / genetics
  • Insulin-Like Growth Factor I / metabolism*
  • Kidney / chemistry
  • Kidney / metabolism*
  • Male
  • Muscle, Skeletal / chemistry
  • Muscle, Skeletal / metabolism*
  • Organ Size
  • Potassium / blood
  • Potassium Deficiency / metabolism*
  • RNA, Messenger / analysis
  • Rats
  • Rats, Sprague-Dawley
  • Receptor, IGF Type 1 / genetics
  • Receptor, IGF Type 1 / metabolism
  • Receptors, Somatotropin / genetics
  • Receptors, Somatotropin / metabolism

Substances

  • Insulin-Like Growth Factor Binding Protein 1
  • RNA, Messenger
  • Receptors, Somatotropin
  • Insulin-Like Growth Factor I
  • Receptor, IGF Type 1
  • Potassium