Effects of insulin-like growth factor I treatment on the molecular distribution of insulin-like growth factors among different binding proteins.
The molecular distribution of insulin-like growth factor I (IGF-I) and IGF-II among the IGF binding proteins (IGFBPs) was studied before and during IGF-I therapy in Ecuadorean adults with growth hormone receptor deficiency (GHRD). Of the total circulating IGF-I and IGF-II, 70% was carried by the 150 kDa complex in normal subjects, while in patients with GHRD, 50% of serum IGF-I, but only 30-35% of serum IGF-II, was measured within the 150 kDa IGFBP-3 region. Administration of IGF-I altered the concentration of IGF-I and IGF-II, although the percentage of total IGF measured within each IGFBP region was not affected, as the increase in IGF-I and the decrease in IGF-II were proportional. Similarly, serum concentrations of IGFBP-3 and the acid-labile subunit, measured by radioimmunoassay, were unaltered. Thus, administration of IGF-I to patients with GHRD was unable to correct the aberrant distribution of IGFs among the IGFBPs.
Gargosky
S E
SE
Department of Pediatrics, Stanford University School of Medicine, California.
Wilson
K F
KF
Fielder
P J
PJ
Vaccarello
M A
MA
Diamond
F B
FB
Baxter
R C
RC
Rosenbloom
A L
AL
Guevara-Aguirre
J
J
Rosenfeld
R G
RG
D000328:Adult; D002352:Carrier Proteins / Q000378:metabolism*; D005260:Female; D006801:Humans; D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I / Q000378:metabolism* / Q000627:therapeutic use*; D007335:Insulin-Like Growth Factor II / Q000378:metabolism*; D008297:Male; D011986:Receptors, Somatotropin / Q000172:deficiency; D011994:Recombinant Proteins / Q000378:metabolism / Q000627:therapeutic use; D013002:Somatomedins / Q000378:metabolism*
D002352:Carrier Proteins; D018969:Insulin-Like Growth Factor Binding Proteins; D011986:Receptors, Somatotropin; D011994:Recombinant Proteins; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II