Insulinlike growth factor I and the kidney.
Insulinlike growth factor I (IGF-I), IGF-I receptors, and IGF-binding proteins are expressed in different segments of the nephron in a relationship that suggests autocrine, paracrine, and endocrine modes of action. IGF-I contributes to compensatory nephron growth in a variety of experimental renal diseases with loss in functioning nephron number, and to tissue repair after ischemic acute tubular necrosis. IGF-I causes arteriolar dilatation in the kidney and increases the glomerular filtration rate in experimental animals, in normal subjects, as well as in patients with chronic renal failure, and this effect of the peptide is probably mediated by nitric oxide. IGF-I raises proximal tubular phosphate reabsorption and may increase sodium absorption in distal tubules. In the nephrotic syndrome, IGF-I- and IGF-binding protein complexes are excreted in urine and IGFBP-3 protease activity is increased, causing complex abnormalities in the IGF-system.
Feld
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Division of Nephrology and Hypertension, Harbor-UCLA Medical Center, Torrance, CA 90509, USA.
Hirschberg
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