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4106880 
Journal Article 
Effect of captopril, losartan, and bradykinin on early steps of insulin action (Retracted article. See vol. 65, pg. 1128, 2016) 
Carvalho, CRO; Thirone, ACP; Gontijo, JAR; Velloso, LA; Saad, MJA 
1997 
Yes 
Diabetes
ISSN: 0012-1797
EISSN: 1939-327X 
46 
12 
1950-1957 
English 
9392479 
WOS:A1997YH80500005 
has retraction 4099723 Statement of Retraction. Effect of Captopril, Losartan, and Bradykinin on Early Steps of Insulin Action. Diabetes 1997;46:1950-1957. DOI: 10.2337/diab.46.12.1950
has retraction 11896993 Expression of concern
Insulin initiates its metabolic and growth-promoting effects by binding to the a subunit of its receptor, thereby activating the kinase in the beta subunit. This event leads to tyrosyl phosphorylation of its cytosolic substrate, insulin receptor substrate 1 (IRS-1), which in turn associates with and activates phosphatidylinositol (PI) 3-kinase. The clinical use of ACE inhibitors has been associated with increased insulin sensitivity. However, the exact molecular mechanism is unknown. In the present study, we examined the phosphorylation status of the insulin receptor and IBS-I, as well as the association between IRS-1 and PI 3-kinase in the liver and muscle of 20-month-old rats treated acutely with captopril, using immunoprecipitation with antipeptide antibodies to the insulin receptor and IRS-1, and immunoblotting with antiphosphotyrosine and anti-PI 3-kinase antibodies. Insulin stimulation increased receptor autophosphorylation to 462 +/- 253% (P < 0.05) in the liver and 697 +/- 78% (P < 0.001) in the muscle of ACE inhibitor-treated rats. There were also increases to 250 +/- 17% (P < 0.001) and 280 +/- 50% (P < 0.05) in the insulin-stimulated IRS-1 phosphorylation levels in the liver and muscle, respectively, of animals treated with captopril. The insulin-stimulated IRS-1 association with PI 3-kinase rose to 305 +/- 20% (P < 0.001) in Liver and 267 +/- 48% (P < 0.05) in muscle. Losartan, an ANG receptor blocker, had no significant effect on insulin-stimulated IRS-1 phosphorylation in both tissues. The acute administration of bradykinin increased insulin-stimulated tyrosine phosphorylation of the insulin receptor and IRS-1 in the liver and muscle. These data demonstrate that ACE inhibitors modulate the early steps of insulin signaling, and that this effect may be simulated by the administration of bradykinin.