Inhibition of calcium uptake by somatostatin in isolated rat islets of Langerhans.

Somatostatin (1 mug/ml) inhibited glucose (16.7 mM)-stimulated 45Ca uptake by isolated rat islets incubated in media containing no added calcium or calcium at a low concentration (0.2mM). Epinephrine (50 mug/ml) and mannoheptulose (20mM) also inhibited 45Ca uptake by islets incubated in the presence of calcium (0.2mM). Addition of glucose (16.7 mM) caused a small but significant increase in insulin release from islets incubated in media containing no added calcium. In the presence of a low concentration of calcium (0.2 mM), glucose caused a much greater increase in insulin secretion which was inhibited by addition of somatostatin, epinephrine or mannoheptulose.