Cyb5r3 Regulation of Insulin Secretion Ex vivo. (A) Glucose-stimulated insulin secretion and (B) insulin content in wildtype islets transduced with Ad-shCyb5r3 or Ad-shScr (n = 3 per group). (C) Representative calcium level traces measured by Fura2AM fluorescence in Insulin2-Gfp primary β cells transduced with Ad-shCyb5r3 or Ad-shScr (n = 10–20 per group). Black arrow denotes point at which perfusion changed from 2.8 mM to 16.8 mM glucose. Red arrow denotes addition of 40 mM KCl. (D) Averaged maximal peak heights of the 340/380 ratio from the same experiment as in (C) (n = 3 plates per treatment, with 10–30 beta cells counted per plate). (E) Insulin (red), Cyb5r3 (green), and DAPI (blue), (F) Insulin (red), Glucagon (green), Somatostatin with Pancreatic Polypeptide (blue), and DAPI (white) immunostaining in 2-month-old B-Cyb5r3 vs. RIP-Cre+ control mice (n = 3 per group). All data are presented as means ± SEM. *p < 0.05, **p < 0.01, ***p < 0.001 by Student t test.