Krebs ringer s buffer

The isolated islets were cultured with DSCC or FB cells in Krebs-Ringer's Buffer (Sigma) at 37°C for 1 hr after 3 or 7 days of coculture. The supernatant was then replaced with Krebs-Ringer's Buffer with 2 mmol/L or 20 mmol/L of glucose and cultured for 1 hr and stored for insulin detection. Insulin was measured by ELISA (Crystal Chem., Chicago, IL).

According to Wang et al [19 (link)] and Naoaki Sakata et al [20 (link)], fresh islets isolated from WT or PD-L1^-/- mice were cultured in Krebs-Ringer’s Buffer (Sigma, MO, USA) at 37°C for 30 min. Then, the supernatant was replaced with Krebs-Ringer’s Buffer containing 5 mmol/L or 20 mmol/L glucose. After incubating the culture for 60 min in 37°C, the supernatant was collected and stored at -80°C for insulin measurement by a sensitive insulin enzyme-linked immunosorbent assay (Crystal Chem., Chicago, IL, USA). The stimulation index was calculated by dividing the insulin release following high glucose by the insulin release following low glucose.