Fig. 3.

Effects of UCP2 over-expression on cellular ATP levels in islets exposed to glucotoxic conditions. At the end of the 7-day culture period at either standard glucose (11 mM) or glucotoxic condition (30 mM), WT and RIP-UCP2 islets transduced with Ad-ATEAM were pre-incubated for 1 h at 2.8 mM glucose before ATP monitoring by FRET, first at low glucose (2.8 mM) before acute stimulation with 22.8 mM (Glucose). Overall mitochondrial contribution to ATP levels was determined by further addition of 2 mM of the mitochondrial poison azide. (A) Signals were acquired every 15 s and kinetic data were normalized to the azide response for WT (orange lines) and RIP-UCP2 (blue lines) islets cultured in standard (11, dashed lines) or glucotoxic (30, solid lines) conditions. (B) Corresponding quantifications of glucose-stimulated ATP rise shown as fold changes over basal levels. (A) values are means ± SE; *p < 0.05 wt 30 versus WT 11 (orange*) and RIP-UCP2 30 versus RIP-UCP2 11 (blue*), #p < 0.05 RIP-UCP2 30 versus WT 30; (B) *p < 0.05 RIP-UCP2 30 versus RIP-UCP2 11; #p < 0.05 RIP-UCP2 11 versus WT 11. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)