Figure 5

Insulin secretion in Hepa1-6 cells expressing the beta-cell specific transcription factors is increased by treatment with L-arginine. A. Insulin secretion in Hepa1-6 cells expressing PDX-1, NeuroD1 or MafA individually or in combination was determined using a mouse insulin ELISA kit. After incubation with the corresponding adenoviruses, the cells were incubated first over night with 1 mM glucose and then transferred to KRB buffer containing 25 mM glucose. Total insulin secretion is expressed as μU/ml * 10⁶ cells. B. Hepa1-6 cells expressing all three transcription factors, PDX-1, NeuroD1 and MafA were incubated for 1 h in KRB buffer containing 1 mM glucose with or without 20 mM L-arginine and 100 μM L-NNA. The amount insulin in the media was quantified by an insulin ELISA assay. The data are averages of five (n = 5) independent experiments.