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Type: Artigo de periódico
Title: Angiotensin Ii Induces Tyrosine Phosphorylation Of Insulin Receptor Substrate 1 And Its Association With Phosphatidylinositol 3-kinase In Rat Heart.
Author: Saad, M J
Velloso, L A
Carvalho, C R
Abstract: We have investigated whether angiotensin II (AII) is able to induce insulin receptor substrate 1 (IRS-1) phosphorylation and its association with phosphatidylinositol 3-kinase (PI 3-kinase) in the rat heart in vivo. The phosphorylation state of IRS-1 following infusion of insulin or AII via the vena cava was assessed after immunoprecipitation with an anti-peptide antibody to IRS-1 followed by immunoblotting with an anti-phosphotyrosine antibody and an anti-PI 3-kinase antibody. Densitometry indicated a 5.6 +/- 1.3-fold increase in IRS-1 phosphorylation after stimulation with AII and a 12.8 +/- 3.1-fold increase after insulin. The effect was maximal at an AII concentration of 10(-8) M and occurred 1 min after infusion. There was also a 6.1 +/- 1.2-fold increase in IRS-1-associated PI 3-kinase in response to AII. In the isolated perfused heart the result was similar, showing a direct effect of AII on this pathway. When the animals were pretreated for 1 h with DuP 753, a non-peptide AII-receptor 1 (AT1 receptor) antagonist, there was a marked reduction in the AII-induced tyrosine phosphorylation of IRS-1, suggesting that phosphorylation is initially mediated by the AT1 receptor. We conclude that AII stimulates tyrosine phosphorylation of IRS-1 and its association with PI 3-kinase. This pathway thus represents an additional signalling mechanism stimulated by AII in the rat heart in vivo.
Subject: Angiotensin Ii
Electrophoresis, Polyacrylamide Gel
In Vitro Techniques
Insulin Receptor Substrate Proteins
Molecular Weight
Phosphatidylinositol 3-kinases
Phosphotransferases (alcohol Group Acceptor)
Citation: The Biochemical Journal. v. 310 ( Pt 3), p. 741-4, 1995-Sep.
Rights: fechado
Date Issue: 1995
Appears in Collections:Unicamp - Artigos e Outros Documentos

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