J Korean Soc Endocrinol.  1996 Jun;11(2):189-198.

Ca Effects on Synthesis and Secretion of Insulin-like Growth Factor(IGF-I) and IGF-Binding Proteins by the Perfased Rat Liver

• Lee DY
• Kang CW
• Kim JS

Abstract

Background
The insulin-like growth factors, IGF-I and -II, are important metabolic factors involved in cell growth and metabolism. The IGFs are produced in most organs but the liver is believed to be the principal source of circulating IGF-I. It has been demonstrated that calcium in the extracellular fluid has effects on the secretion of various hormones such as parathyroid hormone, insulin and atrial natriuretic peptide in variety of tissues. Methods: In arder to investigate that liver produce IGF-1 and IGFBP-3 and the role of calcium in the regulation of IGF-I and IGFBP-3 secretion and synthesis, the rat liver perfusian model was employed. The liver was perfused with Krebs-Henseleit bicarbonate(KHB) buffer containing 0 or 2.5 mM CaC12 for 2 hours, and 4-ml fractions of perfusates were collected and determined the concentration of IGF-I and IGFBP-3 by using RIA after Sep-pak extraction and Western ligand blot. respectively. To increase or decrease the concentration of intracellular calcium, we also used EGTA, calciurn ionophore A23187 increased IGF-I secretion and synthesis in liver(18.13+0.97 vs 15.78+1.01, p<0.01). However, concentration of glucose was not significantly affected by both calcium(2.07+1.44 vs 2.24+1.74) and BGTA(2.01+1A7 vs 3.11+1.01). Conclusion: Our results demonstrate that liver is a major place far IGF-I and IOFBP-3 production and calcium specifically affects the secretion of IGF-I in the liver perfusion, suggesting that the calcium environment of hepatic cells may influence the secretion of the hepatic IGF-I.

MeSH Terms

Animals
Calcimycin
Calcium
Egtazic Acid
Extracellular Fluid
Glucose
Hepatocytes
Insulin
Insulin-Like Growth Factor Binding Protein 3
Insulin-Like Growth Factor Binding Proteins*
Insulin-Like Growth Factor I
Liver*
Metabolism
Parathyroid Hormone
Perfusion
Rats*
Somatomedins
Calcimycin
Calcium
Egtazic Acid
Glucose
Insulin
Insulin-Like Growth Factor Binding Protein 3
Insulin-Like Growth Factor Binding Proteins
Insulin-Like Growth Factor I
Parathyroid Hormone
Somatomedins