Figure 1.

General study design. Standard glucose concentrations in culture media were for rat islets and INS-1 832/13 cells 11 mM (half standard: 5.5 mM) and for human islets 5.5 mM (half standard: 2.75 mM). The media for rat and human islets were renewed to contain standard glucose concentrations before exposure to hypoxia. For INS-1 832/13 cells the media were renewed without changing the glucose concentrations before exposure to hypoxia. Oxygen levels during hypoxia were 0.8 or 2.8% for rat islets and 0.8% for human islets while INS-1 832/13 cells were exposed to 0.3–0.5% oxygen. The media employed in the re-oxygenation period always contained standard glucose concentrations for both islets and cells. (Not indicated are selected experiments in which measurements were made also immediately after hypoxia).