CCK(B) RECEPTOR SIGNALING IN RAT PITUITARY GH3 CELLS - CCK-8S-INDUCEDINTRACELLULAR CALCIUM MOBILIZATION BY CA2+ RELEASE AND CA2+ INFLUX

We describe the effect of sulphated cholecystokinin octapeptide (CCK-8 S) on [Ca2+](i) in rat pituitary GH3 cells. Investigations were perfor med on fluo-3 loaded cells by using a confocal imaging system MRC-600 (Bio-Rad). Because CCK-8S mobilized intracellular calcium in cells bat hed in Ca2+-free buffer it must be able to release calcium from intern al stores. Furthermore, influx of Ca2+ from outside the cells seems to contribute to CCK-8S induced increase in [Ca2+](i) as demonstrated by calcium mobilization in GH3 cells preincubated with thapsigargin in C a2+ containing buffer.