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

We recently cloned the mouse prostaglandin (PG) E receptor EP(3) subty pe that is coupled to adenylate cyclase inhibition through Gi and iden tified 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 influ x from the extracellular medium. This increase was abolished by prior treatment with pertussis toxin (PT). PGE(2) also stimulated an accumul ation of inositol trisphosphate (IP3) in a PT-sensitive manner. Both t he PGE(2)-induced increase in [Ca2+]i and accumulation of IP3 were blo cked by the phospholipase C inhibitor U-73122. Thus, EP(3) is linked t o phospholipase C activation via Gi, and this activation leads to Ca2 mobilization from internal stores and influx from the extracellular m edium. (C) 1994 Academic Press, Inc.