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Obesity Alters Aortic Vasorelaxation Mediated by Insulin and Insulin‐like Growth Factor‐1
Author(s) -
Yang AiLun,
Chao JungI,
Su ChiaTing,
Lee ShinDa
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.lb7-c
Subject(s) - wortmannin , sodium nitroprusside , insulin , medicine , endocrinology , nitric oxide , nitric oxide synthase , phosphatidylinositol , insulin like growth factor , chemistry , growth factor , kinase , receptor , biochemistry
Insulin and insulin‐like growth factor‐1 (IGF‐1) have vasorelaxant effects in vivo, which is dependent on nitric oxide (NO) production. The aim of this study was to investigate the vasorelaxant responses mediated by insulin and/or IGF‐1 in aortas of obese Zucker rats. Insulin‐ and IGF‐1‐induced vasorelaxant responses were evaluated by the isometric tension of aortic rings. The roles of phosphatidylinositol 3‐kinase and nitric oxide synthase in vasorelaxant responses were examined by treating selective inhibitors, such as wortmannin and N ω ‐nitro‐L‐arginine methyl ester (L‐NAME). In addition, the vascular responses to sodium nitroprusside (SNP), a NO donor, were examined. Our results showed that in comparison with age‐matched lean rats, the insulin‐induced vasorelaxation was significantly decreased in aortas of obese rats whereas the IGF‐1‐induced vasorelaxation was significantly increased; after the administration of wortmannin or L‐NAME, the altered insulin‐ or IGF‐1‐induced vasorelaxation was abolished; the SNP‐induced vasorelaxation was not affected in obese rats compared with lean rats. Our findings suggested that the decreased insulin‐mediated vasorelaxation in obese rats appeared to be counteracted by the increased IGF‐1‐mediated vasorelaxation. This study was supported by the National Science Council (Grant No. NSC94‐2320‐B‐006‐062) in Taiwan.