Receptors for insulin-like growth factor-I (IGF-I) in myocardial capillary endothelium of the intact perfused heart |
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| Authors: | R S Bar M Boes A Sandra |
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| Affiliation: | 1. Veterans Administration Hospital, Iowa City, Iowa 52242 USA;2. Department of Internal Medicine, Diabetes-Endocrinology Research Center, University of Iowa Iowa City, Iowa 52242 USA;3. Department of Anatomy, Diabetes-Endocrinology Research Center, University of Iowa Iowa City, Iowa 52242 USA;1. Faculté des Sciences Biologiques, Laboratoire de Recherche sur les Zones Arides, Université des Sciences et de la Technologie Houari Boumediene, B.P.32. El - Alia, Bab-Ezzouar, Alger, Algeria;2. Ecole Normale supérieure de Ouargla, Département des Sciences naturelles, Ouargla, 30000, Algeria;3. Laboratoire de Protection des écosystèmes en Zones Arides et Semi Arides, Université Kasdi Merbah-Ouargla, 30000, Ouargla, Algeria;4. Laboratoire de Biologie des Systèmes Microbiens (LBSM), Ecole Normale Supérieure de Kouba, Alger, Algeria;5. Département de Biologie, Faculté des Sciences de la Nature et de la Vie et Sciences de la Terre, Université de Ghardaia, Ghardaïa, Algeria;6. Department of Life Sciences (DLS), Edward Llwyd Building, Aberystwyth University, Penglais, Aberystwyth, Ceredigion, SY23 3DA, Wales, UK;1. Department of Obstetrics and Gynecology, Meir Medical Center, Kfar Saba, Israel;2. Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel;3. Genetics Institute, Meir Medical Center, Kfar Saba, Israel;4. Faculty of Life Sciences, Bar Ilan University, Ramat Gan, Israel |
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| Abstract: | 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. |
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