HPLC analysis of somatostatin peptides secreted by a rat pancreatic endocrine cell line (RINT3): stimulation studies.

A combination of anion exchange and reverse phase HPLC leading to the purification of a 15-kd proform of somatostatin from culture medium of the pancreatic tumoral endocrine RINT3 cell line is described. Elevation of extracellular calcium concentration causes a dose-dependent stimulation of somatostatin release; maximal stimulation (2.8-fold over basal) was reached with 5 mM Ca. Furthermore, 0.01 microM TPA induced a stimulation of about the same amplitude while forskolin had a low effect. These data suggest that secretion of somatostatin in this model can be regulated by the Ca/C protein-kinase pathway.