Regulation of Hormone Biosynthesis in Cultured Islet Cells from Anglerfish

The effects of glucose and arginine on islet hormone biosynthesis were investigated using primary cell cultures prepared from islets of the anglerfish (Lophius americanus). After dispersion under sterile conditions, islet cells were maintained at$23\textdegree C$in medium containing RPMI 1640 with Hanks' buffer, pH 7.5, modified by the adjustment of glucose (to 0.56 or 5.6 mM) and arginine (to 0.1, 1.15, or 10 mM) with the addition of 10% fetal bovine serum (dialyzed, heat inactivated) and penicillin/streptomycin. After 48 h, media were replaced by incorporation media containing$[^{14}C]isoleucine$and$[^3H]tryptophan$and incubated for an additional 8 h under otherwise identical conditions. Culture samples (cells plus media) were extracted, desalted, and gel filtered to identify and quantitate$[^{14}C]insulin$,$[^3H]glucagon(s)$plus$[^3H]somatostatin-28$, and$[^3H]somatostatin-14$. In some experiments,$[^{14}C]insulin$,$[^3H]glucagon(s)$,$[^3H]somatostatin-28$, and$[^3H]somatostatin-14$were separated by high performance liquid chromatography. Raising the medium glucose from 0.56 (control) to 5.6 mM resulted in an augmentation in incorporation of$[^{14}C]isoleucine$into insulin and an augmentation of$[^3H]tryptophan$into glucagon(s) and somatostatin-14, but no change in incorporation of$[^3H]tryptophan$into somatostatin-28. Raising the concentration of arginine from 0.1 to 1.15 or 10 mM resulted in a dose-dependent inhibition of labeled amino acid incorporation into all hormones except somatostatin-28. The results demonstrate the usefulness of the culture system for studying the modulation of hormone biosynthesis in anglerfish islet cells.