Direct effect of corticosterone upon insulin secretion studied by three different techniques.

The immediate effect of corticosterone upon insulin secretion rates estimated by three different techniques (perfusior of isolated rat pancreas and perifusion or incubation of isolated islets of Langerhans) was studied for one hour. Three corticosterone concentrations were used: 0.02, 0.2 or 20 mg/l. With 4.2 mmol/l glucose, corticosterone did not affect insulin secretion, whereas, with a stimulating glucose concentration (16.7 mmol/l), insulin secretion was inhibited by the three corticosterone concentrations tested during incubation experiments, and by only the two physiological ones (0.02 and 0.2 mg/l) during islets perifusion and pancreas perfusion experiments. Moreover the inhibitory effect appeared more rapid with perifused islets than perfused pancreas, where only the second insulin secretory phase was disturbed.