Rapidly induced modulation of β-N-acetylglucosaminidase activity in pancreatic islets

AbstractThe aim of this work was to determine the possible rapid modulatory effect of glucose on the activity of pancreatic islet lysosomal enzymes. For this purpose, β-N-acetylglucosaminidase and β-galactosidase activities were measured in homogenates of isolated rat islets after a 5, 15, 30 or 60-min exposure to either 3.3 or 16.6 mM glucose. The enzyme activities were determined spectrofluorometrically by means of their respective 4-methylumbelliferyl derivatives as substrates.β-N-acetylglucosaminidase activity measured in freshly isolated non-incubated islets was 5.482 ± 0.281 μmol/mg protein/h at 37°C. In islets incubated with 3,3 mM glucose, this activity dropped significantly after 5 min and remained almost constant until the end of the incubation period. In islets incubated with 16.6 mM glucose, β-N-acetylglucosaminidase activity also decreased significantly at 5 min, and attained its lowest value after 15 min of incubation. After this interval, the activity began to recover and thereafter gained ...