IGF-I and IGFBP-3 transport in the rat heart.
Specific binding of IGF-binding protein (IGFBP)-3 was shown to be present in the isolated, beating rat heart. The uptake of perfused (125)I-labeled IGF-I in the beating heart was decreased to 9% by blocking IGF-I binding sites with the IGF-I analog Long R(3) (LR(3)) IGF-I. When LR(3) was perfused with complexes of (125)I-IGF-I. IGFBP-3, uptake of (125)I-IGF-I was decreased to 41%, which was significantly greater than LR(3) and (125)I-IGF-I (41 vs. 9%). These data suggest that both microvessel IGF-I and IGFBP-3 binding sites contribute to the transport of IGF-I in the perfused rat heart. This also suggests a novel and plausible mechanism whereby circulating IGFs reach sites of IGF bioactivity.
Boes
Mary
M
Veterans Administration Medical Center, Iowa City, Iowa 52246, USA.
Dake
Brian L
BL
Booth
Barbara A
BA
Sandra
Alexander
A
Bateman
Mathew
M
Knudtson
Kevin L
KL
Bar
Robert S
RS
D000818:Animals; D001345:Autoradiography; D001665:Binding Sites; D001692:Biological Transport; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000378:metabolism; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism*; D018974:Insulin-Like Growth Factor Binding Protein 4 / Q000235:genetics / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000008:administration & dosage / Q000378:metabolism*; D007457:Iodine Radioisotopes; D008297:Male; D008833:Microcirculation / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011993:Recombinant Fusion Proteins / Q000378:metabolism
D018972:Insulin-Like Growth Factor Binding Protein 3; D018974:Insulin-Like Growth Factor Binding Protein 4; D007457:Iodine Radioisotopes; D011993:Recombinant Fusion Proteins; D007334:Insulin-Like Growth Factor I