Fig. 2

Effect of forskolin and serotonin on the state of phosphorylation of Na⁺,K⁺-ATPase, DARPP-32, and I-1 in choroid plexus. ³²P-labeled choroid plexuses were incubated for 10 min at 30°C in the presence or absence of 10 µM forskolin (Forsk) and 10 µM serotonin (5-HT). Phosphorylation of Na⁺,K⁺-ATPase was measured as incorporation of radioactivity into the protein. Phosphorylation of DARPP-32 and I-1 was determined in the same samples using a phosphorylation state-specific antibody (see Materials and Methods). (A) Autoradiogram obtained after immunoprecipitation of Na⁺,K⁺-ATPase and separation by SDS-PAGE, showing the incorporation of ³²P into Na⁺,K⁺-ATPase in a typical experiment. (B) Quantitative analysis of Na⁺,K⁺-ATPase phosphorylation determined in three experiments (data represent means ± S.E.M.); *p < 0.05 and **p < 0.01 vs. control. Student’s t test. (C) Western blot showing phospho-DARPP-32 and phospho-I-1.