Figure 2.  .

FSK, an activator of, and SQ22536, an inhibitor of, AC activity, affect photoreceptor growth after 3 days in vitro. (A, B) 0.1, 1, and 10 μM FSK increased the longest neuritic length but not varicosities of rod and cone cells (n = 814 cells; 16 cultures, 2 animals). (C) Radioimmunoassay showed that intracellular cAMP was upregulated by 1 μM FSK after 11 hours and 3 days of treatment (n = 16 cultures, 3 animals). (D) SQ22536 reduced varicosity formation by rod cells at all doses and process number at 200 μM (n = 400 cells; 8 cultures, 1 animal). (E, F) Rod cells immunolabeled for opsin (red) and synaptophysin (green) from a control culture (0.1% DMSO) and a culture treated with 10 μM FSK. Opsin is present throughout the plasma membrane; synaptophysin is present in small varicosities along the neurites (arrows) and in the Golgi apparatus. **P < 0.01; ***P < 0.001; Scale bar = 20 μm.