Details

Autor(en) / Beteiligte

• Hamasaki, Y
• Abe, M
• Matsumoto, S
• Ichimaru, T
• Kobayashi, I
• Tanaka, E
• Matsuo, M
• Hara, N
• Miyazaki, S

Titel

Inhibition by dexamethasone of retinoic acid-induced enhancement of leukotriene C4 synthesis in rat basophilic leukemia-1 cells

Ist Teil von

• American journal of respiratory cell and molecular biology, 1994-07, Vol.11 (1), p.49-56

Ort / Verlag

United States

Erscheinungsjahr

1994

Quelle

MEDLINE

Beschreibungen/Notizen

• We investigated inhibitory actions of dexamethasone (DEX) on retinoic acid (RA)-induced enhancement of leukotriene C4 (LTC4) synthesis in rat basophilic leukemia-1 (RBL-1) cells. Cultured cells were preincubated with RA for 16 h with or without DEX, and generation of LTC4 was measured by high performance liquid chromatography in cell-free and intact cell systems. RA (0.1 microgram/ml) significantly potentiated calcium ionophore-stimulated production of LTC4 synthesis. DEX inhibited the RA-induced enhancement of LTC4 synthesis by up to approximately 95% in intact cells when stimulated with calcium ionophore. RA-induced LTC4 synthase activity, which was determined by enzyme assay, was also inhibited by DEX by 65% in a cell-free system. This discrepancy of inhibition between the intact and cell-free systems was due to a partial inhibition of phospholipase A2 activity by DEX in the intact cells. These results indicate that the production of LTC4 is predominantly regulated at a level of LTC4 synthase. The induction of new LTC4 synthase activity by RA and inhibition of the RA-induced activity by DEX are important regulatory mechanisms of LTC4 synthesis.