Fig. 4.

The effect of GT on insulin secretion from INS-1 cells. Cells were preincubated in KRB buffer for 1 h before incubation with GT or LPA. (A) Cells were incubated with GEF at the indicated concentrations in KRB buffer (3.3 or 16.7 mM glucose) for 2 h. (B) Cells were incubated either with GT (30 μg/mL) or LPA (30 μM) in KRB buffer (3.3 or 16.7 mM glucose) in the presence or absence of LPA1/3 receptor inhibitor, Ki16425 (10 μM) for 2 h. (C) Cells were incubated either with ginsenosides Rb₁ (10 μM), Rg₁ (10 μM), or Rg₃ (10 μM), or GEF (100 μg/mL) for 2 h. Insulin concentration of supernatant was measured using an insulin ELISA kit. Data represent the means ± SD of four to six independent experiments; ^∗p < 0.001, versus control (Con).

ELISA, enzyme-linked immunosorbent assay; GEF, gintonin-enriched fraction; GT, gintonin; KRB, Krebs-Ringer bicarbonate; LPA, lysophosphatidic acid.