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Splanchnic exchange of insulin‐like growth factor binding protein‐1 (IGFBP‐1), IGF‐I and acid‐labile subunit (ALS) during normo‐ and hyper‐insulinaemia in healthy subjects
Author(s) -
FernqvistForbes Eva,
Ekberg Karin,
Lindgren Björn F.,
Brismar Kerstin
Publication year - 1999
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1046/j.1365-2265.1999.00775.x
Subject(s) - splanchnic , medicine , endocrinology , basal (medicine) , insulin , splanchnic circulation , insulin like growth factor , hyperinsulinemia , chemistry , blood flow , biology , growth factor , insulin resistance , receptor
OBJECTIVE The main source of circulating IGF‐I, insulin like growth factor binding protein‐1 (IGFBP‐1) and acid‐labile subunit (ALS) is considered to be the liver, but their production rates have not been determined in healthy individuals. Thus, the splanchnic exchange of IGFBP‐1, IGF‐I, ALS and glucose were studied. STUDY DESIGN In five overnight fasting healthy, normal weight men (mean age 29 ± 1 years) blood samples were taken from a hepatic vein, a brachial artery and a peripheral vein in the basal state and during 3 h i.v. infusion of insulin (1.0 mU/kg/min). Normoglycaemia was maintained with a variable glucose infusion and splanchnic blood flow was determined using a constant rate indicator infusion technique. RESULTS The basal net splanchnic glucose output amounted 0.96 ± 0.09 mmol/min and the splanchnic production of IGFBP‐1 was 7 ± 2 μg/min. There was a net splanchnic uptake of IGF‐I (7 ± 2 μg/min) in the basal state, while no significant splanchnic exchange of ALS was found. During the insulin infusion, insulin concentration increased from 78 ± 12 to 660 ± 30 pmol/l, resulting in a complete inhibition of splanchnic glucose production after 40 min of infusion. Splanchnic IGFBP‐1 production rose initially to 13 ± 4 μg/min ( P < 0.05) and then gradually decreased and was completely inhibited at 180 min ( P < 0.05). Insulin infusion influenced neither ALS nor IGF‐I splanchnic exchange. CONCLUSION Splanchnic production of IGFBP‐1 in the basal state was demonstrated and it is completely inhibited after 180 min of hyperinsulinaemia. In contrast to what is generally held, there was no net splanchnic production of IGF‐I in the basal state or during insulin stimulation.