Transgenic UCP1 in white adipocytes modulates mitochondrial membrane potential

To test if mitochondrial uncoupling in white adipocytes is responsible for obesity resistance of the aP2- Ucp transgenic mice expressing ectopic uncoupling protein 1 (UCP1) in white fat, mitochondrial membrane potential (Δ Ψ m) was estimated by flow cytometry in adipocytes isolated from gonadal fat. Ectopic UCP1 (approximately 0.8 mol UCP1/mol respiratory chain) decreased the Δ Ψ m and rendered the potential sensitive to GDP and fatty acids. These ligands of UCP1 had no effect on Δ Ψ m in white adipocytes from non-transgenic mice, suggesting that the function of endogenous UCP2 in adipocytes was not affected. The results support the hypothesis that mitochondrial uncoupling in white fat may prevent development of obesity.