Figure 2.

NAD(P)H FLIM of human islet metabolism. A: Multiphoton FLIM of NAD(P)H in human islets from representative young (24-year-old, ACJ3270) and aged (58-year-old, ACKH054A) donors. Phasor histograms show the frequency distribution of NAD(P)H lifetimes in young and aged islets (20 islets each). Lipofuscin (arrows) was excluded from the FLIM analysis on the basis of its very short lifetime, which forms a tail at the left of the phasor plots (boxes). Scale bar = 5 μm. B and C: Translation of the phasor histogram peaks (1-g_max,s_max) along the 1-g_max axis were used to quantify changes in bound:free NAD(P)H in response to 2 mmol/L glucose (2G), 17 mmol/L glucose (17G), and 17G plus 5 μmol/L rotenone (Rot) (complex I inhibitor). 1-g_max is plotted to give the same directionality as mitochondrial oxygen consumption. Data are mean ± SEM and were compared by two-way ANOVA with Sidak posttest. ****P < 0.0001. D: Islet mitochondrial response to 17G declines with age. Data are 20 islets from each of 10 human islet donors (ACJV399A, ACJY368C, ACJ3270, ACKB319, ACKB044, ACKB010B, ACKH054A, ADAH342, ADAN146A, ADAT167). Donor information is listed in Supplementary Table 1.