Neuropeptide Y (NPY) and somatostatin (SST) attenuate insulin secretion and increase the cellular redox potential from intact islets. A: percent insulin content secreted from intact islets after static incubation at low (LG, 2.8 mM) or high (HG, 16.7 mM) glucose with and without NPY (100 nM, gray) or SST (1 μM, black). Untreated controls are shown in white. Data are mean ± SE; n = 5–11. *P < 0.05, significance compared with untreated control at high glucose levels. B: glucose dose-response curves of percent change in NAD(P)H from untreated intact islets (black circles) and islets treated with NPY (100 nM, gray squares), SST (1 μM, black triangles), or NE (1 μ M, black diamonds) vs. values at 2 mM glucose. Data are means ± SE; n = 3–11. NPY, SST, and NE treatment at glucose concentrations between 5 and 23 mM is significant, *P < 0.005.