Et-1–induced IL-8 mRNA expression is independent of IL-1β mRNA synthesis. Confluent CNS-EC cultures were treated with either Et-1 (10⁻⁷ mol/L) or IL-1β (10 pg/mL) in the absence or presence of anti-IL-1β (200 μg/mL) or anti-IL-1 (200 μg/mL) for 1 hour. Control cultures included untreated CNS-ECs and cultures exposed only to anti–IL-1β. Total RNA was isolated from the different treatment groups and probed with ³²P-labeled IL-8 or GAPDH riboprobes. Specific bands for IL-8 and GAPDH were visualized using autoradiography. The bands were identified by their appropriate size (IL-8, 181 bp; GAPDH, 96 bp). Results are calculated as the ratio of the spectrophotometric density measurement of the IL-8 band divided by the corresponding GAPDH band, followed by a comparison of experimental group and control values.