MOUSE PROSTAGLANDIN-E RECEPTOR EP(3) SUBTYPE MEDIATES CALCIUM SIGNALS VIA GI IN CDNA-TRANSFECTED CHINESE-HAMSTER OVARY CELLS

We recently cloned the mouse prostaglandin (PG) E receptor EP(3) subtype that is coupled to adenylate cyclase inhibition through Gi and identified three isoforms which are produced through alternative splicing. In Chinese hamster ovary cells expressing each EP(3) isoform, PGE(2) induced an immediate increase in the intracellular Ca2+ concentration ([Ca2+]i) due to both Ca2+ mobilization from internal stores and influx from the extracellular medium. This increase was abolished by prior treatment with pertussis toxin (PT). PGE(2) also stimulated an accumulation of inositol trisphosphate (IP3) in a PT-sensitive manner. Both the PGE(2)-induced increase in [Ca2+]i and accumulation of IP3 were blocked by the phospholipase C inhibitor U-73122. Thus, EP(3) is linked to phospholipase C activation via Gi, and this activation leads to Ca2+ mobilization from internal stores and influx from the extracellular medium. (C) 1994 Academic Press, Inc.