iNOS expression inhibits protein biosynthesis in primary mouse islets in culture. (A) Pancreatic islets isolated from iNOS knock-out and wild-type mice were stimulated with 40 U/ml IL-1β in the presence or absence of 2 mM NMA for 24 hr. NO production was measured by the Griess reaction. (B) Islets were stimulated with IL-1β for 14 hr and then incubated with 35S-methionine for 4 hr. 35S-methionine incorporation into proteins was measured by scintillation counting after TCA precipitation. (C) Islets were transfected with adenoviral vector carrying LacZ (AdlacZ) or iNOS (AdiNOS) for 4 hr, washed twice with media, and cultured with fresh media. Nitrite was measured at 18 hr and 35S-methionine incorporation in new proteins was determined after a 4-hr labeling interval. All data are expressed as mean ± SD of two independent experiments, each performed in triplicate.