Flavin content of intracellular compartments of pancreatic islets compared with acinar tissue and liver.

The flavin contents of pancreatic islets and acinar tissue, whole pancreas, and liver of the rat were measured fluorometrically. Spectrofluorometric scanning of extracts of islets proved that they contained flavins. The spectra showed excitation peaks at approximately 370 and 445 nm and an emission peak at 530 nm; these values are identical to those of authentic flavins. Pancreatic islets contained 3 times as much flavin as whole pancreas or acinar tissue and 20% more than liver. Forty-six percent of the total islet flavin was in the cytosolic compartment compared with about only 11--12% in whole pancreas or liver. The results raise the question of whether islet cytosol contains a flavin-requiring enzyme important for hormone release.