dibutyryl-cyclic-gmp and aluminum-fluoride

Inositol 2,4,5-trisphosphate irreversibly activated capacitative calcium entry in Xenopus oocytes, whereas guanosine thiotriphosphate (GTP[S]) and AIF4- only activated capacitative calcium entry transiently. Both GTP[S] and AIF4- inhibited capacitative calcium entry activated by thapsigargin pretreatment, but guanosine thiodiphosphate (GDP[S]), inositol 2,4,5-trisphosphate and dibutyryl cyclic GMP did not affect capacitative calcium entry. This suggests the involvement of heterotrimeric GTP-binding proteins in the regulation of capacitative calcium entry. Activation of protein kinase C or cyclic-AMP-dependent protein kinase had profound effects on capacitative calcium entry, which were consistent with the hypothesis that the effects of GTP[S] and AIF4- on capacitative calcium entry may be mediated via heterotrimeric GTP-binding protein stimulation of kinases. Further evidence for this hypothesis was derived from the result that the effects of GTP[S] on calcium entry could be inhibited by the application of the protein kinase inhibitor staurosporine.

Topics: Adenylyl Cyclases; Aluminum Compounds; Animals; Calcium; Chloride Channels; Colforsin; Cyclic AMP-Dependent Protein Kinases; Dibutyryl Cyclic GMP; Enzyme Activation; Female; Fluorides; GTP-Binding Proteins; Guanosine 5'-O-(3-Thiotriphosphate); Inositol 1,4,5-Trisphosphate; Inositol Phosphates; Oocytes; Protein Kinase C; Tetradecanoylphorbol Acetate; Type C Phospholipases; Xenopus laevis