Tissue NO content was measured by using an electron spin resonance spectroscopy (ESR) technique, as previously described (21 (link),31 (link)). Insulin levels were determined using a mouse insulin ELISA kit (Crystal Chem, Downers Grove, IL). Determinations of body lean and fat mass were made in conscious mice using quantitative magnetic resonance (EchoMRI 3-in-1 body composition analyzer; Echo Medical Systems, Houston, TX) in the University of Washington Nutrition Obesity Research Center. Hepatic triglyceride (TG) content was enzymatically measured in liver lysates as previously described (32 (link)).