GTP gamma S-induced Ca2+ activated Cl- currents: Its stable induction by Gq alpha overexpression in Xenopus oocytes

In native Xenopus oocytes, injection of guanosine 5'-O-(3-thiotriphosphate) (GTP gammaS) (30 mM, 5 nl) did not induce Cl- current in 11 out of 22 oocy tes. Injection of increased concentration of GTP gammaS (100 mM, 5 nl) into the oocytes induced Cl- currents in 16 out of 17 oocytes; however, the siz e of the induced currents was extremely varied. In oocytes overexpressing G q alpha, GTP gammaS (30 mM, 5 nl) faithfully evoked Ca2+-activated Cl- curr ents. These results indicate that heterogeneous expression of Gq alpha in X enopus oocytes provides a useful system for studying the functional roles o f Gq alpha in regulating cellular events.