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Chronic effect of insulin-like growth factor I on renin synthesis, secretion, and renal function in fetal sheep
journal contribution
posted on 2001-07-01, 00:00 authored by A C Marsh, K J Gibson, J Wu, P C Owens, Julie OwensJulie Owens, E R LumbersIn the adult, insulin-like growth factor I (IGF-I) increases glomerular filtration rate (GFR) and renal blood flow (RBF) during both acute and chronic treatment. To study its effects on the developing kidney, chronically catheterized fetal sheep (120 +/- 1 days gestation) were infused intravenously for up to 10 days with 80 microgram/h IGF-I (n = 5) or vehicle (0.1% BSA in saline, n = 6). In contrast to previous acute studies in adult rats and humans, after 4 h of IGF-I fetal GFR and RBF were unchanged. Fractional sodium reabsorption increased (P < 0.05). However, by 4 days, GFR per kilogram had risen by 35 +/- 13% (P < 0.05), whereas RBF remained unchanged. Tubular growth and maturation may have occurred, as proximal tubular sodium reabsorption increased by ~35% (P < 0.005). Therefore, despite a marked increase in filtered sodium (~30%, P < 0.05), fractional sodium reabsorption did not change. Although the effects of IGF-I on renal function were delayed, plasma renin activity and concentration were both elevated after 4 h and remained high at 4 days (P < 0.05). Despite this, arterial pressure and heart rate did not change. Kidneys of IGF-I-infused fetuses weighed ~30% more (P = 0.05) and contained ~75% more renin than control fetuses (P < 0.005). Thus, in the fetus, the renal effects of long-term IGF-I infusion are very different from the adult, possibly because IGF-I stimulated kidney growth.
History
Journal
American journal of physiology: regulatory, integrative and comparative physioplogyVolume
281Issue
1Pagination
R318 - R326Publisher
American Physiological SocietyLocation
Bethesda, Md.Publisher DOI
ISSN
0363-6119Language
engPublication classification
C1.1 Refereed article in a scholarly journalCopyright notice
2001, American Physiological SocietyUsage metrics
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No categories selectedKeywords
AnimalsBlood Gas AnalysisBlood PressureFemaleGlomerular Filtration RateHeart RateHydrogen-Ion ConcentrationInsulin-Like Growth Factor IKidneyOrgan SizePregnancyReninRenin-Angiotensin SystemSheepScience & TechnologyLife Sciences & BiomedicinePhysiologydevelopmentglomerular filtrationANGIOTENSIN-CONVERTING ENZYMEGLOMERULAR-FILTRATION RATEIGF-BINDING PROTEINSPLASMA-RENINEXPRESSIONHORMONEFETUSFLOWGENE
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