FMO5 and obesity due to melanocortin 4 receptor deficiency: Our observation of elevatedO2- production and upregulatedp47phox subunit of NADPHoxidase in both aging and obese groups (without interaction between the two)suggests a likely role of NADPH oxidase-dependentO2− release in aging and/or obesity-elicitedcardiomyocyte intracellular Ca2+ handling and contractiledysfunction.