The effect of β3-adrenoceptor (β3-AR) agonists on adipocytes treated or not tr eated with signaling modulators has not been sufficiently elucidated. Using rat epididymal adipocytes (adipocytes) labeled with [ 32 P]orthophosphate, we found that treatment with the selective β3-AR agonist CL316243 (CL; 1 μ M) induces phosphatidylinositol (PI) 3,4,5-triphosphate (PI[3,4,5]P3) production and that this response is inhibited by adenosine deaminase (ADA, an adenosine -degrading enzyme; 2 U/ml), pertussis toxin (PTX, an inactivator of inhibitory guanine-nucleotide-binding protein; 1 μ g/ml), or wortmannin (WT, a PI -kinase inhibitor; 3 μ M). The results showed that CL induced PI(3,4,5)P 3 production in intact adipocytes and that this production was affected by signaling modulators. Taken together, our findings indicate that CL produces PI(3,4,5)P3 in an ADA-sensitive, PTX-sensitive, or WT-sensitive manner and will advance understanding of the effect of β3-AR agonists on adipocytes., Y. Ohsaka, Y. Nomura., and Obsahuje bibliografii