FIG. 1.

Insulin secretion in response to glucose, amino acids, and GLP-1 stimulation in transgenic or adenoviral-driven expression of mfat-1 islets or INS-1 cells. A: Islets isolated from the transgenic (mfat-1) or wild-type (wt) mice were incubated with different concentrations of glucose in the presence or absence of GLP-1 (10 nmol/l) for 30 min. The medium was harvested for the measurement of insulin concentration. B and C: Isolated islets from wild-type mice (B) or INS-1 cells (C) were preinfected with adenovirus carrying mfat-1 or lacZ genes for 24 h before the study of insulin secretion, as outlined in A. D: Islets isolated from wild-type and mfat-1 transgenic mice were incubated with 1.1 mmol/l glucose in the presence or absence of 10 mmol/l leucine (Leu) and 10 mmol/l glutamine (Glu) for 60 min before the medium was collected for measurement of secreted insulin. In A–D, the levels of secreted insulin (ng/islet) in each panel were the means + SEM of three independent experiments with each condition carried out in five or six replicates and 10–20 islets in each replicate. ^#P < 0.01, *P < 0.05 when compared with the control group.