Receptors for insulin-like growth factor-I (IGF-I) in myocardial capillary endothelium of the intact perfused heart.
Isolated intact, beating hearts were perfused with HPLC-pure [125]-IGF-I (1 ng/ml) alone or [125]-IGF-I (1 ng/ml) plus varying concentrations of unlabeled IGF-I (10-3,000 ng/ml) or unlabeled insulin (1,000-100,000 ng/ml). After 1 min of perfusion with peptides, the hearts were rapidly fixed, sectioned and analyzed for radioautographic [125I] grain counts. Greater than 90% of [125I] grains were shown to represent intact [125I]-IGF. Maximal grain counts over capillaries occurred after perfusion with [125I]-IGF-I alone and decreased in a dose-dependent manner when unlabeled IGF-I was coperfused. Coperfusion of [125I]-IGF-I with unlabeled insulin also decreased 125I grains over capillaries but less potently than unlabeled IGF-I. EM radioautography demonstrated that [125I]-IGF-I grains were localized over capillary endothelial cells. Thus, specific IGF-I receptors are present in the capillary endothelium of the intact heart and have properties similar to IGF-I receptors in cultured capillary endothelial cells.
D000273:Adipose Tissue / Q000098:blood supply; D000818:Animals; D002196:Capillaries / Q000378:metabolism; D002417:Cattle; D002850:Chromatography, Gel; D003331:Coronary Vessels / Q000378:metabolism*; D004727:Endothelium / Q000378:metabolism; D066298:In Vitro Techniques; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D010477:Perfusion; D011956:Receptors, Cell Surface / Q000378:metabolism*; D017451:Receptors, Somatomedin
D011956:Receptors, Cell Surface; D017451:Receptors, Somatomedin; D007334:Insulin-Like Growth Factor I