GW: Stimulation of insulin release by glucose is associated with an increase in the number of docked granules in the beta-cells of rat pancreatic islets. Diabetes

Electron microscopy and quantitative stereological techniques were used to study the dynamics of the docked granule pool in the rat pancreatic -cell. The mean number of granules per -cell was 11,136. After equilibration in RPMI containing 5.6 mmol/l glucose, 6.4 % of the granules (700) were docked at the plasma membrane (also measured as [means SE] 4.3 0.6 docked granules per 10 m of plasma membrane at the perimeter of the cell sections). After a 40-min exposure to 16.7 mmol/l glucose, 10.2 % of the granules (1,060) were docked (6.4 0.8 granules per 10 m of plasma membrane). Thus, the docked pool increased by 50% during stimulation with glucose. Islets were also ex-posed to 16.7 mmol/l glucose in the absence or presence of 10 mol/l nitrendipine. In the absence and presenc