Glucose-stimulated insulin (a–c), PPY (d), and SST secretion (e, f) from isolated PI of Wistar and Goto-Kakizaki rats during aging. GSIS or glucose-stimulated secretion of PPY or SST was assayed for isolated PI of Wistar “W” and Goto-Kakizaki rats “G” of age in weeks indicated by numbers. Panels (a), (d), and (f) show insulin, PPY, or SST, respectively, in pmol per
μg DNA, pg per
μg DNA, or pg per ng DNA, released before (gray or white bars) and after glucose addition (black or dashed bars), while panel (b) repeats displays of insulin released after glucose addition (black or dashed bars) and compares them with magnitudes of a “recovery” established 60 min after the return into the low-glucose basal medium (horizontally dashed bars), and panels (c) and (e) show the calculated insulin (c) or SST (e) glucose-stimulation index as ratio of insulin or SST, respectively, released after versus that before glucose addition. ANOVA yielded ∗∗∗
p < 0.001, ∗∗
p < 0.05, or ∗
p < 0.1; from the following ensembles: n = 10–14 in (a–c) (5–9 for 56 weeks), n = 5–8 in (d), and n = 5 in (e, f).