Neurotensin Stimulates Inositol Phospholipid Metabolism and Calcium Mobilization in Murine Neuroblastoma Clone N1E-115

Abstract

: Murine neuroblastoma cells (clone N1E-115) possess neurotensin receptors that mediate cyclic GMP synthesis. Because of the hypothesized relationship between phospholipid metabolism, intracellular Ca 2+ , and cyclic GMP synthesis, we determined with these cells the effects of neurotensin on 32 P labeling of phospholipids, release of inositol phosphates, and intracellular Ca 2+ (as determined with the use of Quin-2, a fluorescent probe sensitive to free Ca 2+ levels). Neurotensin stimulated incorporation of 32 P into phospholipids, especially phosphatidylinositol and phosphatidate. Neurotensin also stimulated the release of [ 3 H]-inositol phosphates with an EC 50 of about 1 n M . Mean basal Ca 2+ concentration in these cells was 134 n M and this level was increased in a rapid and dose-dependent manner by neurotensin, with an EC 50 of 4 n M . Since the EC 50 for neurotensin in stimulating cyclic GMP synthesis is 1.5 n M and the K D for binding of [ 3 H]neurotensin at 0° is 11 n M , all these different effects appear to be shared proximal consequences of neurotensin receptor activation.