Fig. 3.

iNOS deficiency ameliorated attenuated IRS-1-mediated PI3K activation in skeletal muscle of burned mice. At 3 days after burn injury or sham burn, insulin (5 U/kg BW) or saline was injected and 90 sec thereafter skeletal muscle was taken. A, B, Insulin injection resulted in a robust increase in binding of p85 PI3K to IRS-1 in sham-burned mice, as judged by immunoprecipitation (IP) with anti-IRS-1 antibody followed by immunoprecipitation (IB) with anti-p85 antibody. However, insulin failed to increase p85 binding to IRS-1 in burned wild-type (WT) mice. iNOS deficiency (−/−) significantly improved insulin-stimulated binding of p85 to IRS-1 in burned mice. The protein expression of p85 was not affected by burn injury or iNOS deficiency. The overall interaction between genotype and other factors (burn/sham and insulin/saline) is statistically significant for binding of p85 PI3K to IRS-1 (P<0.05). ***P<0.001 vs sham-burned WT with insulin, §§P<0.01 vs sham-burned iNOS −/− with insulin, †P<0.05 vs burned WT with insulin. n=4 per group of animals with saline, n=8 per group of animals with insulin. C, PI3K activity was evaluated in vitro phosphorylation of phosphatidylinositol (PI). Insulin-stimulated PI3K activity was decreased in burned wild-type mice relative to sham animals. iNOS deficiency almost completely reversed decreased PI3K activity in burned mice. The overall interaction between genotype and burn/sham is statistically significant (P<0.05). **P<0.01 vs sham-burned WT, †P<0.05 vs burned WT. n=4 per group.