Premium
The effect of an intravenous infusion of IGF‐I and insulin on IGFBP‐1, IGFBP‐3, acid labile subunit, free and bound IGF‐I, catecholamines and potassium in normal volunteers during an amino acid and glucose clamp
Author(s) -
RussellJones D. L.,
Umpleby A. M.,
ShojaeeMoradie F.,
Boroujerdi M. A.,
Jones R. H.,
Baxter R. C.,
Sönksen P. H.
Publication year - 1997
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.1365-2265.1997.3161133.x
Subject(s) - medicine , endocrinology , insulin , chemistry , insulin like growth factor , glucose clamp technique , pancreatic hormone , growth factor , insulin resistance , receptor
OBJECTIVES To investigate the effects of IGF‐I and insulin at doses equipotent with respect to hypoglycaemic effect on IGF‐I concentrations (free and bound), IGF binding proteins, catecholamines and potassium levels. DESIGN A glucose and amino acid clamp technique was used to investigate the effects of a 3 h intravenous infusion of either IGF‐I 43.7 pmol/kg/min (20 μg/kg/ h) or insulin 3.4 pmol/kg/min (0.5 mU/kg/min). MEASUREMENTS Circulating levels of total IGF‐I, free and bound IGF‐I, insulin, IGFBP‐1, IGFBP‐3, ALS, catecholamines and potassium were measured. PATIENTS 6 normal human volunteers aged 21–49. RESULTS During the IGF‐I infusion, IGF‐I levels increased ( P < 0.01) (26.6 ± 2.8–88.9 ± 14.2 nmol/l) and insulin levels fell ( P < 0.05) (16.7 ± 2.9–7.2 ± 1.6 mu/l). During the insulin infusion, insulin levels increased ( P < 0.01) (11.7 ± 1.6–56.7 ± 16 mu/l) and there was no change in IGF‐I. There was no significant change in IGFBP‐3 or ALS during the IGF‐I or insulin infusions. There was a significant ( P < 0.05) fall in IGFBP‐1 levels from 27.1 ± 4.1–8.06 ± 1.6 μg/l during the insulin infusion and a significant ( P < 0.05) rise during the first 120 min of IGF‐I infusion from 28.6 ± 6.3–67.9 ± 10.6 μg/l. There was a significant ( P < 0.05) increase in free IGF‐I and IGF‐I bound to the 150 and 50 kD plasma fractions during the IGF‐I infusion. At basal and the end of the IGF‐I infusion adrenaline levels (pmol/l) were: 173 ± 22 and 174 ± 28; dopamine levels (pmol/l) were: 415 ± 87 and 470 ± 87; plasma potassium (mmol/l) was 4.2 ± 0.06 and 3.56 ± 0.13. At basal and the end of the insulin infusion adrenaline levels (pmol/l) were: 160 ± 38 and 163 ± 21; dopamine levels (pmol/l) were: 238 ± 26 and 316 ± 31; plasma potassium (mmol/l) was 4.2 ± 0.07 and 3.92 ± 0.17. There were no significant changes in plasma catecholamine concentrations with either infusion but potassium concentrations were significantly ( P < 0.05) reduced during the IGF‐I infusion. CONCLUSIONS We conclude that an infusion of IGF‐I resulted in increased levels of both free and bound IGF‐I. IGF‐I and insulin under conditions of adequate substrate supply have acute effects on IGFBP‐1 and potassium physiology, but have little effect on IGFBP‐3, ALS or catecholamines.