Vol. 284, Issue 1, E237-E239, January 2003
REPORT
IGF-I and IGFBP-3 transport in the rat heart
Mary
Boes1,
Brian L.
Dake2,
Barbara A.
Booth2,
Alexander
Sandra3,4,
Mathew
Bateman3,
Kevin L.
Knudtson2,4, and
Robert S.
Bar2,4
1 Veterans Administration Medical Center and
Departments of 2 Internal Medicine and
3 Anatomy and Cell Biology, 4 Diabetes
and Endocrinology Research Center, The University of Iowa, Iowa
City, Iowa 52246
Specific binding of IGF-binding protein
(IGFBP)-3 was shown to be present in the isolated, beating rat heart.
The uptake of perfused 125I-labeled IGF-I in the beating
heart was decreased to 9% by blocking IGF-I binding sites with the
IGF-I analog Long R3 (LR3) IGF-I. When
LR3 was perfused with complexes of
125I-IGF-I · IGFBP-3, uptake of
125I-IGF-I was decreased to 41%, which was significantly
greater than LR3 and 125I-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.
perfused heart; endothelial function; insulin-like growth factor I; insulin-like growth factor-binding protein-3
