CHARACTERIZATION OF TACHYKININ MEDIATED INCREASES IN [CA2-HAMSTER OVARY CELLS EXPRESSING HUMAN TACHYKININ NK3 RECEPTORS(](I) IN CHINESE)

The nature of the senktide response of the human NK3 receptor expresse d in Chinese hamster ovary cells was characterised using the Ca2+ sens itive dye Fura-2 and imaging methods. Application of the NK3 receptor agonist senktide caused an increase in [Ca2+](i) in the cells. The pro file for NK3 receptor agonists was that senktide was more potent than [beta-Ala(8)]neurokinin A-(4-10) which was more potent than [Sar(9),Me t(O-2)(11)]substance P. SR 48968 was a poor antagonist of the senktide response in intact cells confirming the weak affinity of this agent f or the NK3 receptor (IC50 of similar to 1 mu M) shown in binding assay s. The NK3 receptor mediated increase in intracellular Ca2+ was indepe ndent of [Ca2+](o), blocked by the microsomal Ca2+ ATPase inhibitor th apsigargin and the phospholipase C inhibitor U73122 but not by ryanodi ne. Thus the source of the Ca2+ was probably a ryanodine insensitive, inositol triphosphate sensitive intracellular store.