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Effect of hypoxia on lung, heart, and liver insulin-like growth factor-I gene and recep...
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Effect of hypoxia on lung, heart, and liver insulin-like growth factor-I gene and receptor expression in the newborn rat
作者:
David Y. MD Moromisato,
Mark Y. BA Moromisato,
Stefania MD Zanconato,
Jr Roberts,
Jo Anne MD Brasel,
Dan M. MD Cooper,
期刊:
Critical Care Medicine
(OVID Available online 1996)
卷期:
Volume 24,
issue 6
页码: 919-924
ISSN:0090-3493
年代: 1996
出版商: OVID
数据来源: OVID
摘要:
ObjectivesWe examined the effect of 7 days of hypoxia in the newborn rat on: a) body, heart, and lung growth; b) circulating insulin-like growth factor-I (IGF-I); c) lung, heart, and liver IGF-I gene expression; and d) lung IGF-I type 1 receptor gene expression and IGF-I receptor binding. We hypothesize that hypoxic exposure would modify body and organ growth and alter IGF-I gene and receptor expression in an organ specific manner.DesignRandomized, controlled prospective study.SettingUniversity research laboratory.SubjectsEleven newborn rat litters (n equals 10 per litter) comprised the hypoxia-exposed group and 11 litters comprised the control group (room air).InterventionsHypoxia-group rats were placed in a chamber with an FIO2of 0.12 on postnatal day 1. Control group rats breathed room air. Exposure to hypoxia continued for 7 days.Measurements and Main ResultsHepatic, lung, and cardiac IGF-I mRNA levels and lung IGF-I type 1 receptor mRNA were analyzed, using the ribonuclease protection assay. Crude membrane extracts were used for competitive binding studies with IGF-I and insulin. Somatic growth in the hypoxic group was reduced by 22% (final weight: hypoxic, 14.8 plus minus 1.2 g; control, 17.1 plus minus 1.5 g; p less than .001). The relative weight (organ weight/body weight [mg/g]) of the heart was increased by 39% (p less than .001) in the hypoxic pups compared with the normoxic animals, while the relative weight of the lung was unchanged. With hypoxia, IGF-I mRNA concentrations were significantly increased both in the heart and lung (30% and 33%, respectively, p less than .02); but, in contrast, IGF-I mRNA concentrations were not significantly different in the liver. The IGF-I receptor mRNA in the lung was increased by 200% (p less than .02) in hypoxia compared with controls. There was no effect of hypoxia on specific or nonspecific binding of IGF-I or insulin in the lung tissue. However, specific binding was 33% greater in the IGF-I compared with the insulin experiments.Conclusionsa) Hypoxia increased IGF-I mRNA in the heart, and increased both IGF-I mRNA and IGF-I type 1 receptor mRNA in the lung. b) The effects of hypoxia on IGF-I are tissue-specific.(Crit Care Med 1996; 24:919-924)
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