Insulin secretion of Langerhans islets incubated with amino acid. Insulin secretion from isolated pancreatic islets incubated at 8.3 mM glucose in the absence or presence of leucine, isoleucine, valine, lysine and threonine, a cocktail of the 5 amino acids or a cocktail + GIP. Values are means ± SEM for 8 observation in each group performed at three different occasions. The experiments were performed on the islets isolated and pooled from 6 different NMRI mice. Values with different letters are significantly different, P < 0.05.