| Autor: |
Russell-Jones, D.L., Umpleby, A.M., Shojaee-Moradie, F., Boroujerdi, M.A., Jones, R.H., Baxter, R.C., Sonksen, P.H. |
| Zdroj: |
Clinical Endocrinology; December 1997, Vol. 47 Issue: 6 p685-691, 7p |
| Abstrakt: |
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 mug/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 mug/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 mug/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. |
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