Modulators of cyclic AMP in monolayer cultures of Y-79 retinoblastoma cells: partial characterization of the response with VIP and glucagon

VIP markedly stimulates intracellular cAMP accumulation in the human retinoblastoma Y-79 cell line. cAMP increased about 5-fold above the basal level with 10-8M VIP and reached a maximum level (about 70-fold increase) with 2×10-6M VIP. Glucagon at 6×10-8M significantly increased cAMP accumulation with a maximal response at 4×10-7M. Secretin was only effective at micromolar concentrations. Glucagon at 2×10-6M had a synergistic effect with VIP at 2×10-8M. of other substances tested, L-isoproterenol (25-fold increase) and PGE1 (4-fold increase) were most effective. These results demonstrate that VIP and glucagon modulate cAMP accumulation in Y-79 cells and provide a model for studying the effect of these substances on function of neuronal and on malignant cells in vitro.